going from memory here, so take it with a grain of salt...I want to say they’ve said Reason’s UI will run off the GPU, if you have one. I could be mistaken, but I don’t think that’s currently the case.
as for how that will impact performance, it’s hard to say. I tried going back to using Digital Performer last year, and it actually ran worse (both audio and graphics) for me when it was rendering using the graphics card. I hope that won’t be the case with Reason, but I’ll have to wait and see.