I dont agree that it only runs on newer machines.
I started running it last november on an AMD Athlon 2100 XP cpu based pc with 768mb DDR ram.
It only had an old GeForce MX 440 agp card so I couldnt use the "aero" desktop features but other than that it ran fine.
I think that operator errors are more to blame for people not liking Vista rather than the actual OS itself