In the PM you said you bumped your card to 500MHz......500MHz is stock dude.
Make sure you aren't accidentally raising the '2d' mode which means while it's in windows. You want to adjust the performance 3d mode.
Do a bench like 3dmark03 or aquamark (dont do 05, because it's so intense it takes a nice big OC to notice in that program)
stock is 500/900 assuming you're on AGP, if it's PCI-E then it's 500/1000
That card will handle 530MHz core no problem and upwards of 1100 on the agp and 1200 on PCI-E if not further depending of of course the quality of the card.
Bump the core up in 5MHz increments doing that 'test card' before you apply it....go to 530, don't worry it'll be completely safe there.
Then change the memory to like 950 just for the time being. If you haven't had your card for very long it won't want to bump too far on the memory right away but rest assured after burn in time it'll go much further.
Try 530/950 run aquamark or 3dmark03 and you'll definitely see a performance boost