New Wireless Desktop Can't Connect

I inherited a Windows XP desktop with a Linksys Wireless-B PCI Adapter.  I cannot connect to the internet. The desktop can see the Network (2WireXXX). I got the network to work once by allowing Windows to "Repair Wireless Network Connection"  but I lost the network when I had to reboot the desktop.  That no longer works. I don’t know what I’m doing and don’t have manuals for the PCi Adapter. A wireless laptop works fine. Can anyone help?