well, there's a setting in configuration to connect only when a print command is issued, or something like that, and you have to setup and verify the driver for that. There will be a green check mark there. You can uncheck this whole feature, which means you either connect to it all the time, or manually connect when you want to print. I think those two options don't require you to have specific drivers, the vista defaults will do.
OR, may you just have the same problem the rest of do; you can see your device for a few hours or a day, but then it disappears and you have to close down shareport, reboot the router, then restart shareport.