Hi Hugh…
technically….if it’s a PCIe card, sure it will be compatible with your station
The bigger issue is that, as far as PPro CS4 is concerned, it won’t change your performance at all.
PPro CS4 makes really next to no use of GPU technology. So it’s not money well spent.
CS5 has introduced the Mercury Playback engine that will make use of NVIDIA Cuda compatible GPU’s. You’ll have to check Adobe’s site for supported cards.
Other than than that….your system seems quite well configured.
Hope that helps…
Alex