Way back when it was a concern when the 2.4GHz Pentium 4 was out there because a lot of the signals in that PC would be around the WiFi frequencies. Did you try changing the router's WiFi channel?
Recently I've had an issue with my Wireless network that to me seems incredibly strange. I have a desktop hardwired to a ubee DDw3611 modem/router which up until a couple of days ago worked fine. However since then, whenever I turn my desktop on the wireless network becomes inaccessible (it's visible but i can't connect to it with anything). As soon as i turn my desktop off, the wireless goes back to working fine. Any help would be greatly appreciated.