Halp with the Internet

My internet is seriously GHEY. The internet on the computer I'm using works (thankfully, this is the computer that has Warcraft but unthankfully, it's not the computer I usually use) but the other computers in the house (my more usually used computer and my mom's laptop) don't have internet connection. It used to work but now it just doesn't. The icon on the taskbar even says that it's connect but it must be lying, or something. Either that or there is an error while the internet sends and receives. :\ Halp?

1. Faulty modem
2. Internet Leechers (Check for some kind of cord from your house to their or somethin').
3. Bad service provider

..and the list goes on.

router?

WE NEED HARDWARE INFO MAN! 

If you have a router, that may also be causing it.

There may be also some interference with it, you may have to switch the room your computer is in.

If you have a router, that may also be causing it.

There may be also some interference with it, you may have to switch the room your computer is in.

I've had problems with my router all the time, I've never had to take any computer or the router ro a different room.

I had to, some interference with something in the wall 

Limited or no connectivity?

Could just try somthing that cleans all crap like temp files from site, after i did that it ran like a bitch try ccleaner or Cleanup!