Connectivity issues when 2 computers operating at same time

I have a netgear rangemax router and one computer is hardwired into it and a second computer is using the rangemax pci card. I have good connection speed when I am using one computer only (regardless of computer) but if the 2nd computer is being used at the same time, both computers slow to a crawl and sometimes each takes 30-45 seconds to navigate from page to page. Its like they are fighting for the connection. Often one computer loses connectivity (ie when other computer is navigating to a page) and takes awhile to regain connection. Once it has the connection, the other one suffers. I have broadband and this occurs when just doing simple page navigation.

Any ideas? Thanks!