Thanks for everyone's input! After reading, I think I've decided to try to find the Radeon 9000 (64MB one) for around $50 if I can. I will probably check out ebay. There seems to be a few 9000s on there. If I don't find get one for around that price, I will probably just skip the upgrade altogether.
I probably won't upgrade to Tiger until I get my G5. And the 9600 as someone mentioned is AGP8x, so I won't be able to get it anyway.
Besides, $50 doesn't seem so bad of an upgrade for one more year. I mean, I will most likely get a G5 one year from now. I am on a tight budget, so I don't think I would like to spend more than I have to until I get a real job.
Also, when does Tiger come out anyway?
By the way, my friend is selling his GeForce 4 MX that his G4 used to have. Should I just get that instead of the Radeon 9000? He'd prob sell it to me for cheap.