I say... whatever is free... unless you want to get about 10-15 more games running... Then go 64 bit... But other then those 10-15 games, it doesn't make a difference. (and only makes a difference I belive if you have an intel dual or quad core... AMD dual core doesn't seem to like the games that the 64bit likes)
But if you favorite games are rygar and archon... then they will all do.