Winsupersite.com is carrying a run down of the expected versions of Microsoft Windows Vista, to be released Q3/4 2006.
Firstly I think splitting Windows into 7 versions is a bad idea, for Microsoft that is. It will confuse customers into buying the wrong version for their needs and having to buy another version, though this could be the plan $$$. Vista Professional Edition looks the best choice in my opinion. It contains all the features most people will need and allow the enthusiast to work without hardware limits.
It might be found that different versions perform better for different tasks. Vista Ultimate Edition is being targeted towards gamers. Serious gamers already spend alot to make their machines run games as fast as they can, tweaking Ultimate Edition to run them better (or the others worse) means gamers will pay extra, more $$$ for Microsoft.
Apart from being designed for 64-bit systems Vista seems to offer very little that is new. Hardware requirements mean most people will have to build a new system to get the best out of it. This is down to all the 'eye-candy' it includes. So it looks nicer than 2k & XP, is it worth the upgrade cost? My opinion, NO. DRM schemes will tie data on your system down, this might not be a big issue now but once the consumer sees what problems it causes it soon will be.
What will I do?
My choice is to switch to Linux when I move to a 64-bit system. Its a cheaper upgrade as I wont need new hardware and the software is stable. Since the release of XP we have recieved 2 service packs, 2k has had 4. These are now said to be more secure. Vista will have bugs and hardware issues, even if I take the plunge to get Vista to use as a test machine I will wait until after the first service pack. I'd advise new buyers to wait 12 months after release at minimum for minor flaws to be discovered and understood. I'm currently running 2k as I feel its stable and hasn't got the extra crap added to XP. However 2k is an old OS and is not fully supported by Microsoft anymore. I will probably retire it from my main machine in the next 2 years. In the long run Linux will be my choice, I don't want to be tied down and restricted to what I am 'allowed' to do with the OS.
What should you do?
Stay with your current version of Windows. Unless you 'need' features in Vista its not worth the upgrade. Users of 2k switch to XP, gain a few more years support on a reasonable platform with out extensive upgrading. If 'eye-candy' is your thing look at Mac OS X, Apple have been doing nice graphics for a while and have a friendly platform some people might like. Give Linux a try, Live CDs are floating around the net and on magazine covers. They allow you to run a linux environment from CD without altering your windows system. Because its free there is nothing to lose by trying. Most of all consider the alternatives, don't mindlessly choose Windows Vista just because Microsoft makes it. Choose an OS that lets 'you' do what 'you' want.