Vista OEM version ok for use with Parallels?

I just ordered a 4gb macbook pro and want to use Vista with Parallels. So I'm wondering which license I should get, I see that there is a Vista Ultimate upgrade version, an OEM version and a 32 bit and 64 bit version.

Should I get the 64 bit version OEM? Would this work? I really don't know the difference between the difference bit versions or if the OEM would even work, thanks!

Yes, an OEM copy would work just fine.

Thanks Kash, what about the 32 or 64 bit? Don't know much about the difference, which would be best for a intel core 2 4gb macbook pro?

According to the Boot Camp instructions, you can only use the 32-bit version.