you probably first need to decide what sort of connections you want i.e. regular ethernet connections or wireless. wireless is generally more expensive but its great to be able to surf from where ever your laptop is. further if you go down the wireless route you need to choose b or g configurations. in my experience you get better converage with a b type router but slower connections (11Mbps vs 54Mbps) but if you are just surfing the net then this is unlikely to bother you.
Back last december I bought a "Netgear Cable/DSL Wirless Router MR814v2".
It can 'hard' connect 4 computers plus the WiFi function
Have had no problems and even if you don't use Wifi yet it might be worth getting it now.
The main point is I paid $50 for it then in the US (probably even cheaper now), price in UK is still closer to £100. Buy in the US if you can!
I've got AOL broadband and their recommended Wireless router Thompson Speedtouch
Works fine. One PC is upstairs on wireless link. Other is downstairs ethernet attached.
Took a bit of setting up tho'. Had to use help desk because manuals didn't cover all problems.
I've connected a Mac and a Windows laptop to NTL broadband with a Netgear RP614 router. It has room to connect two more PCs if necessary. It doesn't have wireless capability but it was cheap and has worked perfectly for two years. The software was easy to install and configure too.