Should I really be using windows 7 "64bit" with these specs ?

[jim]

A Windows 7 licence is valid for both 32-bit and 64-bit, whether OEM or retail - the OEM version only comes one disc whereas the retail pack comes with both, but if you can source the alternative media elsewhere (MSDN/Technet, borrow it off a mate etc), you can use your existing product key and the resulting installation will be completely legitimate.

So it is. Didn't know that previously.

No argument then, x64.