video card upgrade for mac pro 1.1

I have this machine below; is there anything I could buy to upgrade the video? I recently bought something that wants a gig of video ram:

Model Name: Mac Pro
Model Identifier: MacPro1,1
Processor Name: Dual-Core Intel Xeon
Processor Speed: 2.66 GHz
Number Of Processors: 2
Total Number Of Cores: 4
L2 Cache (per processor): 4 MB
Memory: 6 GB
Bus Speed: 1.33 GHz
Boot ROM Version: MP11.005C.B08
SMC Version (system): 1.7f10
Serial Number (system): YM642 *UQ2
Hardware UUID: 00000000-0000-1000-8000-0017F203AC3E

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