I found this page at Adobe: http://kb.adobe.com/selfservice/viewContent.do?externalId=kb404898#supported Lots of interesting tidbits, most notably this: "Advanced Drawing functions are not supported on PowerPCs, even with a supported display card. When the Advanced Drawing option in Advanced Settings is unavailable, Photoshop turns off Move Color Matching to the GPU, 3D GPU features, and uniform size checkerboard compositing." As it turns out, few PPC GPUs qualify for CS4 OpenGL anyway...but even if you have one, half the functions are greyed out. I tried a few PPC GPUs to see which ones had support: Radeon 9800 - NO Radeon X800 XT - NO Nvidia 6600GT (AGP) - YES Nvidia 6800GT - YES Nvidia 7800GS (AGP) - YES I am going to try a 6200 PCI & AGP but my MDD doesn't see them and my Sawtooth and QS don't have CS4 on them yet. Will be funny if a puny 6200 can shoulder past the 9800/X800s. I was glad to find that there were some cards that worked on PPC, but saddened to see the PPC support waning from Adobe already. Also interesting that if it weren't for card flashing, only the 6800 GT & Ultra would give this support to AGP G5s and there would be NO SUPPORT for G4s.