Hi,I have a rig with multiboot options for XP and Vista. I

You know, I've heard of people doing both.but I would install it on the same drive as vista so you can have a separate CFG file for DX10 etc etcI think it would work though the way you want to do it

That's how I've got mine set up--I originally only had Vista (with FSX) installed, and I later put XP on a separate partition.Once in XP, it was just a matter of hitting FSX.EXE on the Vista drive, and I was set -- I get quite a performance boost on XP over Vista.You don't need to worry about FSX.CFG -- FSX will make a new one automatcally on the XP drive, and your old FSX.CFG will still work if you still want to run FSX on Vista.Good luck!