There are long answers and there are quick answers. Obviously my answer is drawing a distinction between moving to a new PC with 7 (some call this an upgrade) or attempting to install 7 onto their current PC. My recommendation referring to the latter.
It is doubtful that a users PC bought a while ago will have hardware that can take full advantage of 7. This includes all internal and external peripherals and the issue is drivers. Not being able to use an internal or external audio / video / control surface with 7 due to a lack of a driver may be a show stopper for some. I have never been able to use all working audio devices when changing OS, and know of many faced with having orphaned thousand dollar peripherals by "upgrading" their OS. Since this is a Video / Audio forum, it is one of the relevant costs to the upgrade. (Finding driver, installing, testing, etc. etc.)
The best feature of 7 is the hardware aware virtualization, but like the XP Mode (actually it's the basis of the XP Mode afaik) is only available with the real version of "Pro" as you mentioned. If you look at the cost of the full version, and the cost of new PCs - it becomes doubtful. The software applications are another story.
There is a cost with any OS upgrade which far surpasses the cost of the OS software. Most of us use our PCs for many purposes. The time lost in configuration and compatibility problems is huge.
My recommendation, stay with the OS the PC came with until you absolutely need new hardware. An alternative is upgrading RAM, Disk (solid state and hybrid solid state) and even processor are often possiblities to improve performance which are more cost effective and less risky. Upgrading disk to a hybrid drive is probably the best and most cost effective idea right now.
Many get caught by urges to always upgrade to the latest. If you really need 7, buying a new PC can be the best choice. Your old PC can be the backkup.
Different opinions abound. Your polite inquiry contrasts greatly with the venom I felt when suggesting that "upgrading" to Vista was a bad idea, and that "downgrading" to XP was recommended. Subsequently, M$ offered XP downgrades to businesses, and many retailers sold PCs and laptops with "XP downgrade" as an option.
I won't address the question of software applications and my answer holds even assuming that 7 can fully support all older x86 apps and environments. Perhaps most importantly for some are other issues associate with both Vista and 7 in terms of security, privacy, etc. which go far beyond this post.
Other than that, I've heard 7 is great, and far far better than Vista. Of course, ymmv.
we took everything we needed off the computer, wiped it and installed windows 7. I guess the disc will do an install that wipes your computer for you, just don't forget to take everything you need off it first. studio works great with windows 7. And, now, I can watch the raw footage from my T2i before I process it, without the choppiness. I edit in HD and I can have lots of clips on my timeline now whereas before, I had to limit the number of clips that were on the timeline because the program would crash.
Definitely agree that 7 is much better than Vista. My understanding is that 7 is more demanding on hardware that Vista, and also that device drivers must be rewritten for certain peripherals.
If getting a new PC, yes "upgrade" to 7. But my my response was assuming by "upgrade" the OP meant replaceing the OS on his current PC.
Just offering my opinion, I'm sure 7 is working great for many. Of course, each is best to make hisr own decisions based upon his own circumstance.
I've found it is very is to wind up spending more time on being a PC tech than on content generation, and upgrades are potentially a huge time sync. Often, the PC can't be fully used when there is an issue, which in audio/video work can often be buggy or missing device drivers for the new OS. If it's your "production" PC it's a real issue.