This is a long shot but Windows Vista (and possibly Win7) have a network security lan manager authenticiation level. I had to fix this for my Vista machines to see Novell and SME shares.
in regedit
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\| Lsa
Change LMCompatibilitylevel to 1
Reboot and see if you can see shares. As I said, its a long shot, I don't have Win7 here yet to test with.