Got two computers running XP Home connected via a Router/Switch. Neither has ICF enabled on the LAN connection. Both have NetBIOS over TCP/IP turned on and both have the Computer Browser service Started. Both machines can Ping the other by IP and computer Name. Both have folders shared.
Computer A can browse and see the shares on Computer B no problem.
Computer B can Map a share from Computer A, but cannot browse Computer A. (It gets a "\\computerName is not accessible" error.)