are there items one can buy to help boost or extend our Wi-Fi internet connection better


We have several devices hooked up to our Wi-Fi from AT&T, and we are pretty sure we have the absolute best package available for this area. It's a pretty congested area with mobile homes close together and sometimes the Internet is way slow. I bought a Linxys (probably spelling it wrong) for my PC because it's not a laptop and needs something plugged into it. My family has cell phones and sometimes they game, and what I haven't been able to do lately with a lot of success is use my Victor Stream or Blindshell phone without at least a few times a session being told error and error is always about the connection. My littler items are having a hard time staying connected and this hardly ever happens when I'm at other places with less stress on the Wi-Fi or the towers or wherever the problem is. I mean I am right here by this Linxys thing when using these items but it still acts up more than it should. If I go closer to the actual Wi-Fi in the living room I seem to have better luck downloading or web-surfing, etc. Do I need something super-strong in my room, or is there some kind of booster that might distribute Internet access better? Do you think it's my PC, since it's an older PC but I didn't think it would affect how my connection with the Linxys comes across.
I really would appreciate some thoughts on this one.

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