Hi this is my first posting on this forum so Hi!
You could use 64bit fedora on 32bit XP *IF* the processor supports hardware virtualisation
I had a 64bit OS running on my HP Pavilion laptop running 32bit XP Home edition, The vmware player allowed the guest os to see a 64bit cpu, rather than a virtualised 32bit one.
Sorry if this upsets some people. *IMHO* It's a valid reason to post here as he's asking about running linux 64bit.