From what I can tell, your problem was with the gpu number being wrong in the OP with a single card. One gpu is gpu 0, not gpu 1. You have to have a dummy plug in XP when you extend the desktop to the second monitor, or it won't let you extend to it. You can take it off after that. In my experience, the "gpu not supported" error means you haven't extended the desktop to the other gpu. Let me know if this helps, I've had to go through this before too, I've folded with XP (32 bit) and Vista x64. I've run the systray client and the console version too. You can edit the client.cfg file to set any parameters, like -gpu0, etc.