If it's near appliances move it. Try to get it in the center of your house or if you only use it in one area move it closer to there. Anything else that is wireless could cause interference (ie: some mice, speakers, phones)
You could also try upgrading the hardware, you didn't list the brand/model/year so I don't know. I get good signal from my wireless on my blackberry while I'm outside my apartment and I can go pretty far before it starts to dim