You don't really give enough details. Will your IPAQ connect to a different network? Will it connect to your friend's network? Or can your friend connect to yours? - That will narrow down the problem to your network and not the IPAQ or vice versa.
Can the IPAQ 'see' your network but not connect? In which case in could be an authentication issue. Try turning off your WEP/WPA security briefly to see if it connects then.
If it can't see your network at all, do you have your SSID broadcast disabled - you can check this in your router settings.
Hope these suggestions help a bit = if you have any further details, I'm sure someone here will be able to help.