my rig won't even stutter on uncompressed footage, you're probably better off looking at game benchmarks.
drivers usually won't lead to any noticeable improvement in display quality.
if you're curious about how video cards compare to eachother, look at the tom's hardware vga charts
a high end video card won't really help you play back amv's, or really help in rendering (save for 3d rendering...but if you really need tons of power for that you're better off getting a nVidia quadro or ATI fireGL card)
right now my rig specs are:
Athlon64 X2 3800+ (s939, overclocked from 2.0 to 2.4GHz)
2GB OCZ platinum dual-channel ddr400 (2-3-2-5, 2.75V)
1GB corsair valueselect dual-channel ddr400 (2-3-2-5, 2.75V)
2x 36.7GB raptors in raid0 (10,000 rpm)
1x 320GB WD caviar (7200rpm, this is what I play my amvs off of)
HIS Radeon x1950pro (factory overclocked to 590 core / 770 mem)
if you want to hear my analysis of your rig just post your specs