BT routers are actually quite good and reliable.
BUT, I wouldnt run computers directly from it, it isnt very good as a hub and I think they only run at 10mb instead of 100mb.
Get a nice 5 port netgear switching hub and then connect your 4 computers into this. Then run another lead from the router into the netgear port which is labelled auto detect uplink.
You will be suprised at the network speed difference.