For what it's worth - I had exactly the same problem - same set up - when I started down the wireless road. Two pain-filled days talking to a very impatient guy in an Indian call centre - who knew his stuff - but it was a major pain. Now I've gone and bought some HomePlugs to see if that gives me a more robust home network and guess what ..... sigh

For anyone who hasn't got a wireless router yet and is thinking of doing so, the people at Belkin were superb when my wireless connection stopped working. Sorted everything out over the phone in 5 minutes.