internet loading issues

I have a new iMac 10.10.1 desktop connected to a surfboard modem provided by my cable company. I have an old Belkin wireless router hooked up for my laptop running win does 7. Internet loads slow and stops altogheher on the mac but not the laptop.

Which new router would you recommend to solve the problem?

Can you explain the connections again, please?
Are you cascading routers there? ie, surfboard router connected to 2nd router by ethernet cable? This method very much complicates the setup and results.
Compare the local IP addresses of the two computers. (you can tell us the local IP addresses because no one can get to (hack) those through the first router. Local-only IP addresses begin with 192.168 or 10.0 or 172.x. Don't publish IP addresses ouside of those ranges.)
Which computer is connecting via wifi to which router?

PS - you should have given us this extra detail in the other post, too.