Wireless speed goes from fast/slow w/full signal

I have a mac book, and have run into a problem with my houses local wireless network. The whole time I'm connected to the network I have full signal strength. However, my internet speed goes back and forth from fast/slow/fast/slow and sometimes I get disconnected from AIM it's so slow. I tried turning on "interference robustness" but that didn't help. I even tried moving closer to the wireless broadcaster that only helped marginally. Any help would be greatly appreciated.
Thanks,
-Greg P