Yes, you have to backup everything and then you need to download 64-bit drivers. If some hardware is old, it is far easier to find 32-bit drivers than 64-bit. That's why I avoid 64-bit version, unless the computer has more than 4GB RAM. For up to 4GB RAM 32-bit version is just fine and you won't miss a thing, apart from small exceptions such as Hyper-V. But Hyper-V would hardly work or would be very slow with only 4GB RAM, anyway.