ATY RadeonX1900 replacement

Hi,

I have a Mac Pro1.1 with 2x 2.66 GHz Dual-Core Intel Xeon, 3GB 667 MHz DDR2 FB-DIMM.
My current graphic card (ATY Radeon X1900) started displaying corrupted images and I am looking for a replacement. Could anyone please recommend a decent graphic card I could use with my computer?
My budget is up to £250.

Thanks!