Wireless Help - Excellent connection, no internet.

Sorry to be another one of the two million posts about this but, I recently purchased a Dell Inspiron 5150. Everything was fine for awhile, then one day my internet started to get slow. It would take literary 5 minutes for a page to load and another 5 minutes for aim to connect. Well, As of today It takes atleast 15 minutes for the page to load and I cant even connect to aim.

My Wireless connection usually has a Good to Very Good connection. I have DHCP setup. And it is working fine. Receiving the IP of 172.22.1.100. I can ping websites fine. No requested timeouts. I can also use aim's configuration tool to find an open port so I can connect to them.

But either websites says "page has not been found" or takes literary 15 minutes too load. And aim takes about 5 minutes too load if I am lucky. Most of the time I cant even connect.

I know it is not a problem with my wireless router because We have 2 other computers connecting through wireless and they have no connectivity problems.

I have even reformated my HD and installed XP pro SP1. Yet I am still receiving the same problem. I have connected to the network at my work using ethernet and got amazing speeds. So Ive narrowed it down to the wireless acting up or My network malfunctioning, But i dont see how it is my network if 2 other computers are able to connect perfectly.

So this is my last resort, hopefully someone from here can help me.

Thanks in advance!!!