For basic file sharing, Sharepoints will work. In fact I'm buying an old B&W for my server over the summer. Basically if you'll want non-admin Windows users to login (basically guests) you'll have to create a guest account (do it in Sharepoints because it can create homeless accounts) and give it read only access. Otherwise windows computers will have admin access to all your files. OSX client is the same as OSX server, only sever has nice GUI programs to edit server options while you'll have to do it manually in OSX client. Sharepoints does take away some of the burden.