Router slows connection

Hello,

I have a Netgear WGr614v10 wireless router and a comcast cable modem, I have 2 computers connected to the router. 1 computer runs fine and has a great connection but the second computer times out and can barely load a page on the internet. When I connect the computer directly to the modem it runs fast but then slows down to a crawl when I connect it to the router.

Please help