Running my current system on the specs I have listed with Vista X64 and not having any probs at all. When I first installed it was quite sluggish as I only had 1Gb ram but with 2 or above it seems ok.
Same thing goes for gaming, I can run most of the new releases in decent enough detail, only game that has caused aggro with my specs has been Crysis but not keen on it anyhow!
Have XP installed on my wifes machine which is a PIII 500 and 512 Ram, bit slow as its an old ide hard disk in there but it manages ok. Its good they are supporting XP up till 2010 but they can only support it for so long before it becomes obsolete. Been out there since 2001 now, 7 years ago it was typically a new OS finding its feet with the same kind of problems Vista has had for its first year.
Now that SP1 is out for Vista it is working much better, drivers are way better than 6 months ago and it works. Its not exactly that wow factor that has been getting plugged but it is a decent OS that is starting to mature.
Mentality of it all comes down to just how long does an OS have a shelf life, Windows 98 was a great OS but it has to be let go to make things move forward within the industry. There are still people out there that I know personally that are running 98 and are happy with it as they don't do games at all. Simply something that is used for kids homework and web surfing. If all the 98 users started putting up petitions to still support that OS after around 10 years of it being in consumers hands Microsoft would end up losing money if they carried on supporting it.
Whether you like Microsoft or not, it is still a business. Businesses are there to make money, especially a business model like MS. They are building Operating Systems that go better with modern up to date hardware. You want the latest and greatest system you may as well take the OS that goes with it. XP is great but it is time for it to start standing down and make way for Vista.
All the hardware manufacturers creating drivers for so many different Operating Systems also costs money which inadvertantly could push prices up. Instead of having to work on older OS drivers every month more time should be getting put into the new OS drivers. Start winding things down so they can put better time into supporting Vista so it has a lot more appeal for everyone.
Personally I love Vista now that SP1 is out, when my wifes machine gets upgraded in the next few month she is going for Vista also. No turning back for us from there!