I am using a dlink wbr-1310 and am able to detect

I am using a dlink wbr-1310 and am able to detect the wireless connection via my HP running vista. Recently had a friend come over and her Vaio running windows xp was NOT able to detect the wireless network. I reset the router twice and even logged in to make sure I wasn't preventing new connections. To no avail. Basically, her wireless connections does not include my network in the list. She's able to connect wirelessly at universities, coffee shops, etc. Any help would be appreciated.