Can you explain why 64bit? =] As far as I know 64 bit has a lot of problems with adobe product and also 64 bit supported applications arent that much on market, although they can support 32 bit too but some of them cant get the extended support for 64 bit processors.
If you are talking about 4 or more than 4 GB Ram support then I think it is supported in Windows 7 or you can tweak it up to support it on 32 bit too.