Just do a search on Windows Vista and my guess is you will get a number of sites that are dedicated to bashing Windows Vista. Countless articles litter the net about how bad Vista is, and all the resources it consumes, and what a hassle UAC is. Blah blah blah...save it!
My guess is, that many of these people never used Vista. They certainly haven't tried it for any great period of time. Many of the problems that were present when Vista first shipped had to do with a lack of decent video drivers, especially from Nvidia. Many other people blamed Vista because their all in one printers didn't work, but the blame should have been laid at the feet of the hardware makers. Many of them didn't write drivers for Vista because they wanted people to upgrade to "Vista Compatible" hardware,rather than enable the older stuff to work.
My own experience with Vista I believe is far more typical of what you would hear from everyday users of Vista, if the pundits bothered to ask. My experience has been quite good,in fact, better than I expected, being am early adopter of an OS that had so many changes from its predecessor. I've been using Vista for 11 months on my primary desktop computer. It's a modestly powered by today's standards,but it does have dual core processor 2 gigs of ram and a outdated Ati Raddeon 1950 Video card. When I first put it together I ran it on integrated graphics with only 64mbs of video ram and aero glass worked fine. The machine has been very stable and the only real crash I experienced was when I tried to install service pack 1. I detailed that in previous posts, but in general it works great, and whenever I go back to XP I always miss many of the features in Vista that make going back to XP not an option. I like the UAC, I know it gets a lot of complaints from some people, but it saved me at least once when I was half asleep and checking email not paying attention, and accidentally clicked on a nasty attachment. The start search is awesome, the ability to find a specific email, document or program before you get half way through typing it is great. There's no 3rd party search that work nearly as well, neither Google's desk top search or Copernic come close. I have even come to really enjoy the sidebar. I have to admit I just turned it off for the first month or two but now I keep track of the weather, a few stocks and my calendar with the sidebar, I find it quite handy, when I'm using XP I'm always looking over for the sidebar or trying to do a start search, and I just think oh, yea it's not there,crap!
As for performance and hardware needs I recently installed Vista Ultimate on a 2 year old Lenovo Thinkpad that shipped with XP Pro and had the dreaded "Vista Capable" logo on it. Now I'm aware Microsoft is getting sued by some people that claim their Vista Capable machines were inadequate to run anything above Vista Home Basic, but the machine I have works fine. It runs an early 1.83 ghz core duo processor and a ati 1400x graphics card with 128 mbs of video ram. I installed 2 gigs of ram, which is a minimum for running Vista. I also upgraded the hard drive since the original only had 60 gbs and I wanted a multi-boot system, I put in a 7200 rpm 200 gb Hitachi hard drive. This machine boots Vista 2 seconds faster to the login screen than XP. Now I'm not saying Vista runs faster than XP, the XP partition has the Lenovo suite of applications they include with new machines and runs Symantec Corporate Antivirus and Firewall. The Vista side has no manufacturer installed "crapware" and runs AVG free version 7.5 . I used MSCONFIG to turn off all but the security software at start up so it a reasonably fair contest.
Now I still think XP is less resource consuming and is slightly faster in running applications once running, its just not that noticeable.(with identical hardware) With Service Pack 1 for Vista installed, it runs even better, file copy is much better and Vista is now compatible with hundreds of programs that originally it broke. There's no doubt XP has evolved into a very solid OS from the buggy and very insecure system it was, when it shipped originally. So if your older hardware still work fine, stick with it, but if your hardware's getting old and its time for an upgrade, don't fear the Vista, don't listen to the so called experts, bashing a Microsoft product takes about as much guts as bashing President Bush right now.