I've been thinking about going back to XP 'till then, but everything's set up under Vista on my laptop here.
I could simply format the Vista partition, then combine it with the one XP's installed on so I have more space to work with, but that means that when the service pack comes out, I've got to go through the fuss of creating that third partition and resizing the others appropriately again.
Actually going to play StepMania for a bit now though, then see about putting more songs on my PSP for PSPRevolution. The ones on there now are getting very old.