I wanna login to Mac servers on my PC
This site may be of assistance.
Sure, if you have admin access to the AFP server.
Open up Server Admin (I think that's the name of it) Utility, go to File Sharing, turn on "SMB" file sharing. IIRC, there is a reference to Win filesharing on that feature.
I know nothing about Vista, but I assume that Win still uses SMB.
Obviously, if you don't have admin access to the server, you'll need to talk the admin into doing it. It's literally a 2 minute task.