The day you buy it, it is already yesterday's technology
You already know enough to not buy Vista. Windows 7 is probably the way to go and just have a plan in mind for updating it as soon as you start to use it becaue by the time you get it there will probably already be patches, etc.
I think instead of focusing on it from this angle, FIRST focus on what YOU want / need to do with it, how much storage and performance you need, if you already have software that can be loaded on or if you need to buy something loaded, etc.
You might be surprised at how little you need.
Then if you want to scan the latest technologies to see if any of them float your boat that is fine. But really, keep your focus on what YOU need and WANT and not "what is available". Evaluate each trend against your needs. It is very possible that there are some new trends which frankly you won't really need or want.
Focusing on what is available is a surefire way to end up with more computer and more bells and whistles than you need.
OPTIONAL MAC COMMENT [-And, I realize you are into Windows and all that,and don't care about Mac, but I will just mention that in an earlier post, I mentioned that one thing which impressed me was my Mac's resale values, which makes it possible for me to always stay current, and I never have to worry about falling out of step.]