well i bought a 256mb ati radeon 9550 128bit agp, and i have a 256mb ati x1300 64bit pci. I was just wondering which would give better performance and if the 9550 supports shader model 3.0 or not? I would assume the 9550 would perform better given that its a 128 bit card although it's older.

The 9550 is a completely worthless card nowadays. An x1300 isn't exactly good, but it's not total junk. And no, the 9550 can't do shader 3.

Moved to Hardware.

PCI is a slow bus, so that's totally against the X1300. However, the X1300 is at least two generations newer than the 9550. The 9xxx series were the first Shader Model 2 cards, and can't do anything beyond plain 2.0.