Didn't realise your 5500 was PCI.
The x1300 comes in a variety of flavours.
X1300 Pro - 600/800
X1300 - 450/500
Be very careful if you decide to get one as all of them come in either 32-bit, 64-bit or 128-bit.
All have 4 pixel pipes and 2 vertex shaders.
As 003 said i would avoid ALL of them!
Athlon 64 3000 E6 Venice @2.43Ghz
Gigabyte 3D Rocket Cooler
ASRock 939 Dual SATA2 Bios 1.20
2x512mb Corsair VS @DDR348 1T
XFX 6800GT PCI-E @400/1100
Maxtor 120Gb SATA
Antec TruePower 550W