I have recently noticed wireless network problems with one of my computer; I'm getting something like 4-6 Mbps of download speed according to Speedtest.net, when I should be getting at least 5x that. I have two other computers connected to the network, and they both get 30-40 Mbps, so it is this machine in particular. The problem persists independently of which browser I'm using, and running an AV scan didn't pick anything up.

I don't have any ideas for what else to try at this point; does anyone have any suggestions?