OS X and network neighbourhood

[TnT]

Samba sharing is called Windows File Sharing in System Preferences -> Sharing

It looks like you've got that okay. To be able to login to it using windows accounts you'll have to set the Mac to work with your Windows directory service / Active Directory. Go into Directory Services -> Services -> Check Active Directory -> Configure, then enter the domain and server.

[The PIT]

Except we're not using active directory on campus I'm afriad.

[TnT]

If you are using only local accounts on the computers, I don't think there is a way to login to the Mac except by creating a local account with the same name and password on both computers.