
So... what is my opinion on this?
1) Everyone using a PC will eventually have to migrate. This is just a fact of life. Windows on 80% of all PCs, combined with MS moving to a new version, means most people will have no choice. That however does NOT mean you should rush out and buy Vista now. I am not saying anything innovative here, but this is what I think based on what I have read so far.
2) WAIT!!! The average piece of computer code has one error every 100 lines or so. Windows Vista contains over 3.5 MILLION lines of code. That translates into a lot of errors, which translates into a lot of problems. To be fair, MS has been testing this for years now to get out as many bugs as they can, but it is a safe bet that you will be reading about Vista problems for the first months.... until they release the inevitable....
3) SERVICE PACK! This will contain fixes for many of the problems that pop up. Most people who went on to Windows XP found that it was not really that good until the SECOND service pack was released. There will be a Vista SP1. Wait for it, there is no advantage to being an early adopter because...
4) WINDOWS VISTA RUNS SLOWER THAN XP ON CURRENT HW. All I have read indicates that most current generation HW will have a slow down in performance running premium vista, due to all the fancy schmancy graphical eye candy thrown in. Intel, AMD and Nvidia are all releasing fairly major hardware changes in the next year, quad-core 45NM processors, new graphics architecture... all of this new stuff will be much better for Vista, but it could be a year before it is optimized and affordable.
5) Wait and see what Apple offers with:

So, those are my thoughts. The takeaway message for this is:
1) If you want a PC, you will eventually have to get Vista, but WAIT!!!
2) Consider a Mac unless you are interested in gaming, but WAIT!!!
overall, now is not the ideal time for a new computer, ask me in 6 months.