Whether 32 or 64bit has nothing to do with display problems except with XP Pro 64 since no one really offered much driver/software support when that editition came out. You are still running a 32/64 type cpu. Eventually all will be 64 only.
Vista is the one to choose for 64bit support while waiting for the next version presently labeled Windows 7 would seem the best move for 64bit likely seeing more 64bit programs out by that time. The best option now would be XP 32 or Vista 32/64.