Ah, my bad - I read that as 8GB (SSD harddisk implied) or 512MB usb drive

AFAIK some of the ATOM models do include 64bit, but the models used in netbooks are 32-bit only - could be wrong, though. But again, even if it supported 64bit, I'd go for 32.
Anyway, there's only "x86_64"? I personally read that as 64bit-only - but it's damn annoying that 64bit x86 has been called so many things, can make the things a bit muddy. Personally I prefer x64, since you can say simple "x86" or "x64", same number of chars. A lot of linux distros prefer "i386" or "amd64", respectively... while I'm not fond of those naming conventions, at least it makes stuff pretty unambiguous. Ubuntu uses this naming scheme, hint hint

Any particular reason you feel like sticking with redhat? It sounds like you've only had relatively limited linux use so far, things that are going to be more or less the same across different distros. Imho Ubuntu is a good choice because it's got a lot of inertia going, and it's relatively easy to deal with - without trying to to clone Windows and such.