Depends on drivers and actual efficiency of graphics subsystems.
Using Vista 32-bit build 5347 and a Geforce 6600 (Not top of range, but not POS either), I get stuttering graphics and slow window movements - even on MPEG-1 playback with 'old-skool' desktop theme (win2k-like)! The machine had a X2 3800+ and 1 Gb of Corsair RAM. Some others have much better rendering using Ati hardware, leading to the idea that maybe Ati's drivers are more accomplished.
Last time I had that bad a stutter, I was trying MPEG playback on a Cyrix P166+ (133MHz - P75-level FPU) with a Trio64 2Mb.
Now, I try SuSE 10.1 and Xgl+compiz on a GF 5200FX (THAT's a POS by today's standards) and it ran... flawlessly. Jelly windows, drop shadows, 3D desktops, window zoom, MPEG playback, real-time window transluscency.. The machine touted a Sempron 64 and 512 Mb of Corsair value, and it still pwned the Vista-installed machine: I could actually work with it.
While Ati may have the best Vista chips and drivers for now, Nvidia's are nothing to sneeze at - it's a matter of tightening drivers