PC F5D7632-4 - Unable To Find Network

I have my downstairs PC (Windows Vista 64 bit) conncted to a Belkin router. model F5D7632-4. This works without any problems.Upstairs, my son has a PC (Windows XP) that connects via a Belkin USB G Network Adapter, model F5D7050, version 4.000uk. This worked perfectly, too.He has just got a new PC which I have bought from a friend. My friend used the tower of a previous PC my son had, which had died about 4 years back when the PSU blew and took everything out with it, and fitted the motherboard, graphics card, HDD, RAM etc etc (it uses Windows 7).

I downloaded the latest drivers from the Belkin site, installed them, but for the life of me, the new PC will not detect the network connection. At all. It doesn't find anything.So, I unplugged my PC from the router, and plugged the new PC into it. Unsurpisingly, it connected to the net without any problems. The next thing I did was to reconnect my PC to the router, and try my son's new PC wirelessly again with the Network Adaptor, in the same room. Again, it just doesn't find a network at all.The PC detects the Adapter being plugged in and out, and the light is on on it. I even tried his old PC with the Adapter, and that still finds the network perfectly.

I was on the phone to Belkin for 35 mins yesterday, and they went through everything, to no avail. They think the USB slots may be faulty, even though the PC knows when i'm plugging things into them.