A lot of people get bitten by the GTHTLAG (got to have the latest and greatest) bug. Symptons include spending hours surfing the web using Price Watch and wandering around places like Best Buy and CompuUSA with a rather blank look on their face looking for the latest computer toys... oops make that computer hardware. :-)
You don't realy need a dual or quad motherboard loaded with 1900 Mhz processors or RAID drives or tons of memory to do video editing. If you're on a budget consider what is now a medium speed processor, like something around 1200-1400 Mhz, use the money you save to buy a bigger hard drive. You can never have too big a hard drive if you do a lot of video editing. In fact you probably would be better off getting two 40 GB drives rather than a single 60 or 80 GB. Reserve one drive just for editing. Memory of 256MB should be plenty, 500MB is better of course, anything more is overkill with today's fast processors. Consider getting a 18-19 LCD monitor. Vastly superior to the older CRT monitors and because the brightness/contrast is on a par with most TV's, you won't attempt to over compensate due to staring at a dull CRT monitor when making color/brightness/contrast adjustments in your video. As far as a operating system, go for XP. It is rock solid and Vegas Video hums along without any hangs. Of course use NTFS for the file system so you can render a humongous SINGLE video file. So far my record topped out at 43.4 GB.