Troubleshooting slow wireless connection

I am stumped. I have a Belkin wireless router, and I'm using a D-Link wireless NIC. I am getting a very slow wireless network connection through my PC only. I did a speed test on my DSL connection, and it came out at 2.5 Mbps download speed. No problem there.

The problem is my wireless network. Even when I just try to go to my wireless router configurations it runs very slow. I thought the problem was my router, because when I connect to it directly with a wired connection it works fast. I brought a laptop home though, and connected it, and the internet, and wireless network was great. I also have a wireless PS3 on this network that works great too.

The next step was to test my NIC. I tried another wireless NIC, and am having the same problem. I am not having any trouble with pop ups or viruses, although I am going to try some deeper scans of these next.

Any suggestions?