if you have 128MB ram that's a reason or you have got the amd agp fix
i went from 128 to 256 mb ram and this fixed those annoying pauses in games ect. It will not give you supper high frame rates, but you will get more consistence performance.
my specs
amd 650 MHZ, AMD 751 chipset
256 MB ram
geforce ddr
8gb HD western digital
sblive value