Networking Woes

I am having some trouble setting up a network between three pcs, each running windows xp. Two of the three are networked just fine, but the third (its using xp 64 bit edition, don't know if this could have anything to do with it) is not sharing its files and printers with the other computers. I have it set up for file and print sharing, and I have also tried disabling all firewalls on the troublesome pc. If I get on one of the other pcs, go to my network places, and then view workgroup computers off to the side, the troublesome pc shows up, but when I double click its icon, it asks me to sign in. I don't have a password on this computer so I try typing in administrator and leaving the password field blank. No good. When I try double clicking the icon of the other computer, it displays that computer's shared folders and printers. What is causing this computer not to network properly and how can I fix it? All suggestions are appreciated!

EDIT: I enabled simple file sharing and things now seem to work. I suppose you have to have simple file sharing enabled for windows to properly set up the default shared docs folder.