Runs quite well on WinXP. There's a quirk with the USB joystick requiring a fix, ranging from unplugging the joy during game loadup to being handled by third party programs. As for sources for purchasing RB3D try a GOOGLE search. Sold Out Software offers a version which doesn't initially install to an XP machine but there's a workaround for that.
RBII can be patched to RB3D. There's also a "Valueline" RBII which can't initially be patched to RB3D but there's a workaround for that as well.
My sig contains links to familiarize those considering the game