Airport Express and windows laptop

Please help. I am running an airport express as my main wireless router. I am on a g4 ibook and am able to access internet flawlessly using the express. The problem is with my wife's computer. She is reading the airport express signal fine, her laptop is working properly, but she keeps disconnecting and reconnecting to the airport randomly. Her connection will work for a few second then disconnect for a few seconds, then reconnect, then disconnect. She is in the same room as th express, so signal strength should not be a problem. I have done everything properly with her notebook, and it seems running fine. Any ideas? And no throwing her gateway out the window and getting her an ibook is not an option in her mind.