Desperate For Help, Wireless Crisis!!!

Hi,

Recently, I've been having this really weird problem with my wireless internet.

I connect to the internet using Airport, through the wireless network in my house, and sometimes (like now) I will get perfect reception and my internet wil run at a normal speed, and other times I will get very little or no recpetion whatsoever.
I've tried running diagnostics, and it says that the network is running fine, and the computer still retrieves my IP address, but it's also running really slowly. I've also moved my computer into another room, but it doesn't fix the problem.
I've had this computer in the same room for months, and this only started about one month ago. Could I have "broken" the Airport in the computer by moving it, or is there a problem with the network itself? (I don't personally think it's the latter, because the other computer in our house isn't having this problem...)

If I've left out any vital information, let me know.

Thank you all so much for your help.

Could be a short circuit to the wireless antenna in your screen. Or a bad Airport card. (Well assuming your using an apple notebook)

I was thinking it could be the Airport card. Can you replace them, and approximately how much would it be?

P.S. I do use a macbook.

Also, is there a way of checking if one of the antennae is not working?

Thanks again for your help.