whats the deal about home groups vs normal file sharing?

homegroups is only for full Windows 7 networks right? i cant use it with XP/Vista PCs?

vista detects the files shared by the homegroup (not as a "homegroup" per say as in win 7 but as a media streaming device).

homegroups adds a layer of security as far as i can see with one password that allows access to those files and printer. no other computer can access this group with that password. however, only your music, documents, videos, and picture can be shared. other folders cannot be shared.

to share other folders, you need to disable the homegroup password security and enable user accounts and password.