Like the other poster said, you're not going to get a huge video speedup with that 128 card. But jag does have a bunch of other small improvments that really add up. It's considerable faster, even without a QE capable card.

I have a G4/667 powerbook, so QE is supported. But it was still a lot faster to boot up and whatnot. Apps bounce less, etc. Get jag, it's what OS 10.0 should have been.