Honestly, I would throw out the homehub piece of crap and get any other modem/router I could. Mine lasted two or three days with problems before it clapped out.
Using the hub (a rebadged Thomson unit, IIRC) I would make sure both wireless units used different channels. Also, I think you need to set the Belkin specifically as a bridge.
Or are you trying to use the Belkin as a "receiver" and have the two PCs wired to that? In which case, I would suggest you lash out about 25-30 quid on a pair of wireless network cards for the PCs.