I routinely max out my 20Mbps cable connection using a WRT54G (of some sort, poss GL) running Tomato. It does struggle with bittorrent, usually if I try and VNC over Hamachi when seeding, I should try and sort that in QoS one day.

Virgin have 100/10 in my area (over coax!) but it is £45/month so I am holding off at the moment, FTTC/VDSL will be availble in April and I would prefer that I think.