Two options:
Replace the router with something like this, you might even be able to get one with wireless for the future for a similar price.
http://www.ebuyer.com/UK/product/52754/rb/24424343043
Option2:
Connect one of these to the back of your current router:
http://www.ebuyer.com/UK/product/8894
And plug the other network devices into that. The jobs a goodun.
However, if you wanted to be a geek, you could run VoIP into every room, using the cabling have. Different extension numbers and a single or multiple incoming phone lines (all via your broadband) for every room. That would be cool
Dan