Changing the channel is a good idea. I should have thought to mention that on baseball101's other question. You should set your router to channel 1 6 or 11. Most routers default to channel 6 and are never changed so if you change yours to 1 or 11 chances are you will have less interference. Scanning with your device will tell you which channel is clearest.
Angling the antenna can help. My router in upstairs and I get the weakest signal in my bedroom. Angling the router antenna so it is perpendicular to my room increases signal strength.
You can try changing your signal channel. Routers have a series of channels, between one and eleven. Change to a channel that will give you a clear signal.
Or, try repositioning your router.
-Raise it up as far as possible to increase the range.
-Place it near the center of your home for wider coverage.
-Move it away from any metal like metal shelves, filing cabinets, etc...
-Move it away from cordless phones, microwaves, etc... because they operate on the same frequency.
Sometimes if you unplug it for 30 seconds it resets it and works stronger. Also, ensure that you have a password protected wireless network...otherwise your neighbors could be hacking into your internet, ultimately slowing down your internet.
You can also purchase a Wireless Expander. It's a little device that plugs right into an outlet and "stretches" the signal. Here's a link to the one I currently use: