Here's the deal... A simple update to 64bit windows 7 won't get you anywhere. Cemu is very demanding and will require a much stronger CPU than the AM2 motherboard will allow. I hate to halter your enthusiasm for emulation and PC building/upgrading, but you're better off saving for a new/used PC with a modern CPU. However, if you still want to update to 64 bit, you can download the ISO file from Microsoft. You'll need to backup your important files and select custom install from the 64 bit Windows 7