router trouble with imacg5,ibook and powerbook

Here is the problem. i live in a house with 3 other people. two pc owners and two macs total. the macs seem to be having some trouble with the router (cheap microsoft router). i get a connection, but no websites work. i can use limewire, ichat(aim) and torrents but pages wont load. can anyone help???? oh yeah, i forgot to mention that the same used to work about 2 months ago. then all of the sudden, it just stopped working.