Vista has a network icon that runs in the bottom right hand corner by the clock that looks like 2
computers with a small globe infront.
If you right click on this icon you can select the "Diagnose and Repair" option.
Vista will look for problems, and if it gives you options to Automatically get new IP settings, click it.
or Reset the network adapter, click it.
After a short delay, Vista should confirm that the connection is working properly.