Don't bother with homegroups. They are a pointless home user feature M$ added to Win 7 that I can see being dropped again in a couple more OSs down the line. Instead just make sure all your PCs are in the same Workgroup and then in Windows 7 in the sharing permissions add the usergroup "everyone" to each system. That will then allow you to access everything within a shared drive or directory that is shared. Must more simple and removes loads of hassles you can have with home groups.