Hi
If it is a modern PC or laptop (but not a netbook) it will be suitable for 32 bit or 64 bit Windows
But no point in upgrading unless you have 4 GB or more of ram
You have to obtain (buy) 64 bit version then re install from scratch including all programs
You can't upgrade from 32 bit to 64 bit
(X86 = 32 bit, x64 =64 bit)
Depending on windows version you may be able to get a download from Digital River who host windows for microsoft
Regards
Mike Barnes