Kate, at this stage, it might be kinder to your PC to do a complete reinstall.
If you want to soldier on, try getting the very latest drivers for your wireless network card using
>this link<. Before you install them, go to Start-->Control panel-->(switch to classic view if necessary)-->System-->Hardware-->Device manager.
In Device Manger, go to Network Adapters, find the Intel 2200BG, right-click on it, choose properties-->Driver-->Uninstall.
Having uninstalled the driver, try installing the one downloaded from Intel. Report back.
I'd have the proposal at the ready, but I think my wife might disapprove.