I'm not using MacDrive at all. It's the AEBS that handles the way the computers communicate with the HFS+ drive, so a third party program is not required to allow Windows machines to see it.
I wish I had my Vista machine with me at the moment, but as it is I don't so I can't be of too much help. The only suggestions I can make are to make sure that your network is set to private in Vista and to make sure that you install AirPort Utility (which comes with AirPort Base Station Agent) directly from the Apple site (making sure it's the latest version) onto your Vista machine.
AirPort Base Station Agent should detect the hard drive connected to your AEBS and mount it automatically on startup.