Could specify a few things...
What exactly is slow?...downloading or just plain opening pages?...could you give an idea of how fast you can download a file from...say download.com(or another reliable fast download site)?
Also, are you connecting via wireless nic or via cables? What is you connection speed?
And when you say cable router, do you mean the router and cable modem are combined in one?
If you transfer files directly from one computer to the other is it also slow?
Just give us a little better idea of the situation and I am sure someone will be able to help.