All i can say about Vista, having a higher and low performance computer/laptop is...
Dell, IBM, Acer, HP and the other should be ashamed of selling Vista on low end and budget PC's, to me its a joke. Yes they meet the "Minimum" standards, but no they dont meet the "Minimum" of what "IS" required to make Vista operate as smooth as XP.
Vista should be titled more like XP Premium or similar as its only good at running on computers that have at least 128 dedicated graphics, at least a gig of ram and at least a 3GHz processor. The most important thing to run Vista is a dedicated Graphics card, if you dont have one then its just not going to run as good as XP.
I have tested it out on both my laptop and desktop and have found my laptop is Flying with Vista on it, it benchmarks higher, hasnt crashed and all that, where as Vista was a nightmare on my desktop, so i have sent it back in time to XP.
My Laptop is well over a year old, and i paid £900 for it, so it wasnt really a massive high spec, but its got 256 Dedicated, 1028 Ram and 2400 CoreDuo and its great as Acer built it from componants that was obviously going to have Vista updates for drivers.
I know that 99% of the world are currently hating Vista, but on the right Machine its Brill, i get 4Fps more out of FSX too, not as i needed any more FPS...