I’m delighted to say that the new antenna on the Buffalo seems to have solved the network problems. 😀
I wish I’d tried it first as the antenna only cost me £3.49 plus P&P and the Belkin was £30. I guess you live and learn.
I’ve decided to keep the Belkin and just plug it in occasionally when I want to go online with my PS3 which is the other end of the house to the router now, but to keep it unplugged the rest of the time so that the SB doesn’t ever try to connect to it.
Thanks for all the help trying to get my setup to work with Firefly though.