Unable to connect beyond IE8

Hello, I've had this problem for a couple of months now and tried to deal with failing at removing it, but a recent move to an apartment with poor wi-fi has finally made me try even harder at getting this fixed. Basically, a couple of months ago, I was doing fine with FireFox until one day, I couldn't download anything or access any websites even though I was connected to the internet. Nothing major happened that I can remember to illicit such a big change in my internet experience.

So, I went back to using IE7 and I found that I could access webpages, but with a catch: I couldn't (and still can't) download pretty much anything. I say "pretty much anything" because as I type this, I am downloading FireFox.

Unfortunately, I am sure that this won't solve my problems: I've done this times before with FireFox, Opera, and Google Chrome, but was unable to access any website off the browser. So while I can download a bit with IE7, I am unable to download or use a lot of stuff that requires an internet connection (think updates from Java, RealPlayer, Adobe, etc.). An interesting this is that I've disabled my Windows XP Updates, but when I allow it to download and reboot, I can't access anything off IE7!!! It just tells me what all the other browsers tell me: they're unable to access the internet due to there being no internet connection (even though there is one).

So, here is my problem: I am unable to establish an internet connection for upgrades even though I am able to access webpages only from my IE7 browser. I am using only IE7, have Windows XP, disabled Windows Update, enabled Windows Firewall (that doesn't help though), and am working with a HP Pavilion dv6000 laptop. Thank you so much for taking some of your time to help me! :-)