Simply, you can't, most games are written for 32bit OS (to keep the Xp luddites happy) and if we are lucky they automatically use any of the features of any 64bit hardware they find. This is nothing to blame on the OS, it's totally down to game developers pushing the formats that most people have to maximise profits... rather than quality. That said, even when developers do add 64bit support you may well still find them located in the programfiles x86 folder.