Well for what it's worth, I took the jump to Windows Vista Ultimate a couple of days after release. I still miss Duke Nukem, but that hasn't run since Windows95. I am mostly happy with it, but there are the odd quirks here and there. My X-Fi sound card will quit working while playing EQ2, but I just downloaded (another) new driver for it today so we'll see how that goes. The transition from XP to Vista seems to have went much better than with other upgrades. Here's a refresher for those who might have forgotten, I'm sure many of you went through the same experiences:
Millennium to XP, never did it, went back to 98SE one week after installing Millennium (Microsoft - I still want my money back for
that upgrade);
98SE to Millennium - see above. 'nuf said other than horrible experience. ( I think I enjoyed visits to the in-laws better);
98 to 98SE - was glad to see that the 9X OS was finally mature. This was the operating system I had been waiting for. The transition was perhaps easier than XP to Vista, but was it really a "newer" OS? No, they just finally fixed everything.
95 to 98 - ouch. Stuff didn't work anymore. I could see DOS based games starting to lose some support (Yes Duke started to suffer

)
3.11 to 95 - hmm what can I say but remember upgrading ALL your hardware first, then wondering where the improvements went? Lost speed, even though we upgraded to a much faster processor, but finally had a visual OS.
I've left out the NT line, and Windows OSes prior to 3.11, I was sure how many actually used those, and those of us who did probably can't remember back that far. (Okay you caught me, that's the real reason - I can't remember back that far

)
Other than the memory requirements, which might be fine for the average user that doesn't have Photoshop, Flash, 2 different web browsers, Dreamweaver and whatever else open all at once, Vista is a pretty great OS. I have 2G Ram, and am seriously looking at upgrading to 4, but other than that I wouldn't go back. To quote a famous wart-hog "You've got to put your behind in the past."
My only advise - run the Vista upgrade analysis tool, see what you might need to upgrade, and take the plunge. The water's warming up!