Just be warned, the latest version of things like Vegas run CPUs at 100% load. What might seem stable when overclocked can come undone when rendering and encoding. Outside of video editing applications there's pretty well no software that'll run a CPU at 100% load for hours.
Bob.

OC'ing also messes up the RAM & AGP timing which caused my a LOT of hair pulling over the winter (I oc'd my AMD 64 3000 to 2.2ghz with the stock AMD heatsink but 3d apps kept crashing. Ends up it was conflicting with the AGP setting. Worked great in Vegas though)

Also, a good cooling system can cost a couple hundred $$$ plus AMD's warrenty doesn't cover OC'ing, so you can save $1-200 & OC or pay the extra & have a warenty. Plus, with the way CPU prices drop after comming out, I just buy 1-2 years behind. 75% off origional price. :)

The main reasons against overclocking are:
A- It takes time to stress test your computer, and also to learn about overclocking and dicking around with your computer.
B- You risk instability!! Sometimes you can stress test your computer and it will still be subtly unstable.

However, overclocking can definitely be worth it. Video rendering is around 90% dependent on the CPU, and overclocking your CPU will definitely speed things up. If you edit professionally/full-time, this can mean serious productivity gains (few, maybe several hundred dollars). If you do want to overclock:
A- Use thermal paste on the heatsink like Artic Silver 5. A lot of 3rd-party heatsinks come with a tube of their own thermal paste. Read the instructions, less is better. Using thermal paste is the most cost-effective way of cooling your processor more (which means more headroom for overclocking).
B- If you can afford it, get a 3rd party heatsink like the Zalman 7700alcu or better, more expensive Thermalright XP-120 + fan (maybe a panaflo, not sure what the best fans are these days). These are among the best heatsinks out there, and they certainly don't cost a couple hundred dollars. The zalman is about fifty and the thermalright around a hundred twenty. (try newegg.com?)
The Thermalright XP-120 performs about as well as low and mid-end watercooling systems.
Check motherboard compatibility on these heatsinks, the size can be a problem. hardocp.com's reviews are very good about this.
C- Use a good set of instructions for overclocking that includes information on stress testing...
for AMD64 systems: http://forums.anandtech.com/messageview.aspx?catid=28&threadid=1497607&enterthread=y
D- Get a platform that is good for overclocking... when AMD64 first came out, the PCI/AGP frequencies weren't locked and that was a problem. Many of the newer chipsets don't have this problem.
hardocp.com's motherboard reviews should give you a good idea of what parts will overclock well. Some motherboards aren't good for OCing (i.e. Intel).

The article is actually pretty thorough in their testing. They are very specific in their test setup, and they don't use any terribly exotic hardware (on purpose) for the testing. They benchmark it on just about every possible use, including video rendering. No, it wasn't rendering for hours on end, so that's a factor, although temperature buildup doesn't appear to be an issue at all.

I certainly wouldn't recommend maximum overclocking to anyone, let alone video editors where a reboot can crush your productivity (as I found out during my Pinaccle Studio days). However, given how easily (if you read the article) this chip overclocked to 2.8Ghz, I wouldn't hesitate to OC this cheap 3000+ chip to the 2.2-2.4 Ghz region (3500-4000+ equivalent). Should have ZERO problems there, and you just saved $200-300 over buying the other chips.

If you have more money than time because you video edit for profit, then you might as well just buy a dual-core and not worry about it. If you're a home user and can afford to test as you rachet up the overclock, why wouldn't you?

Curious if anyone's ever used the manufacturer's warrantee on a CPU before? Seems like it would either work or not, which you should obviously check out prior to attempting to overclock.

The Venice core has the advantage of SSE3 instructions. Can't say how well these have been implemented however the presence in the PIV CPU has arguably given Intel the multimedia edge. AMD have put the shared relevancy (11 of Intel's 13) SSE instructions into Venice Athlon-64-E chips.

The single core Athlon-64-E chips are likely to be good value for money compared to other solutions from any x86 camp. Irrespective of overclocking capability and whether the motherboard assures the correct clocks to the peripheral buses.

Last year was probably for Intel, this year looks like it is more for AMD, so far. If you get the geeky drift of what I am trying to say. ;)

The results do look impressive. Now if only you could do that with Opteron chips!

On the low end, it looks like Intel would be a better choice for Vegas (3.4E, old 865 chipset; this combination is not upgradeable but even newer platforms wouldn't be that upgradeable). Performance-wise, Intel is definitely better at MPEG2 encoding with the Main Concept encoder (Vegas+DVD uses that I believe). At rendertest.veg, it's hard to say because there hasn't been new results lately. But AMD and Intel run neck to neck at "equivalent' clock speeds, with Intel perhaps having a small lead.

On the high end:
As you get into multiple cores and multiple processors, AMD should scale up better because it does not share the FSB, each core has its own dedicated memory controller, NUMA, etc. Once you get into dual core dual Opterons, you may see AMD really pull ahead. Intel doesn't even have dual core Xeons yet, and the chips that come out may debut at lower clock speeds than AMD.
As well, AMD is upping its clock speeds faster than Intel is which means on the high end AMD is going to be doing better.
Also, many AMD64 systems use the cheaper DDR RAM and not DDR2.
And another advantage is that AMD64 systems consume significantly less electricity, which lowers their total cost of ownership. If you leave your computer on 24/7, this can mean substantial savings in electricity. Some people don't pay their own electricity so this wouldn't be an issue.

Something interesting to note is that the Pentium D (dual core single processor) doesn't perform all that fast at the Main Concept MPEG2 benchmarks I've seen at xbitlabs.com.

In the four years that I've had my homebuilt PC, it's seen two motherboards, 4 CPUs, and frequent hard drive/video card/sound card/DVD burner swaps. I've found that some CPUs and motherboards overclock better than others, and in any event you don't want to run so close to the edge of the envelope that the system is unstable. My current setup is overclocked about 10%, and everything is rock stable.

Being a part-time geek, I also run all kinds of monitoring software on the system. I've learned, for example, that my CPU idles at about 53C, heats up to about 60C when doing a long render, and crashes at 64C. I've learned that this PC functions very well as a dust vacuum, and I can see just how much dust the CPU heatsink has picked up by monitoring the gradual rise in CPU temps. About once every 4 months I need to aggressively clean the heatsink.

Overclocking can come in several forms. One way is to raise the clock for not only the CPU but also all the cards sitting on the bus. Here, too, I've found that my WinTV card, my video card, the hard disks, and all the other stuff hanging off the bus can handle a 10-20% boost very well.

Edit: They say that running a CPU really hot will untimately limit its life. I have no doubt that this is true. Still, the CPU that I'm currently running (AMD XP2100) cost me maybe $100 two years ago, and is essentially worthless today. If I'm limiting the chip's life to 10 years from 200 years, I don't care.

BTW: I'm salivating over the new dual-core AMD 64 CPUs. I feel a rebuild coming on in about a year, and maybe a 4x boost in render speed.

The low end Intel probably is better for video than the low end A64, but one nice thing about the 939 socket A64 is that you can build a nice, but cheap computer today and yet still have a simple upgrade to dual core once the prices come down (hopefully in a year or so). Gotta love how cool they run, too.