I think I'm right in saying that AMD processors are comletely (or nearly
enough) comaptible with Intel, at least at 32 bit. I've just been to the
download page (http://www.ubuntu.com/getubuntu/download) and I can't see
the choice between Intel and AMD mentioned.

64-bit processors are dead common these days, however software that makes
use of them is still right rare. 64-bit Ubuntu tends to have problems that
32-bit doesn't, so I hear (and the same with Windows too). Fortunately 32
bit software runs on 64 bit machines. You might want to check some more,
but I think you can go ahead and try it out.

Why not run it up in LiveCD mode anyway (run the operating system direct
from the CD) and if that looks ok go ahead and install.