can't connect to any web sites or do emerge once installed

[mpeg4v3]

I recently got to college and brought down two computers. The second one, I had installed Gentoo on prior to coming down here, since I am a complete linux noob and wanted to learn. Everything worked fine, and I was able to emerge everything, get KDE setup (after like 2 days of compiling, geez), but then I emerge'd openoffice, and that error'd out after about a day and somehow that screwed up my entire install, so instead of trying to fix it I just reformatted.

The first time I reinstalled, I couldn't emerge anything. During the install, after booting from the LiveCD, it worked. However, as soon as I finished the install and rebooted into the shell for the first time, none of the mirrors worked. Every mirror it selected would time out, not a single one would work, despite the fact on this computer, my main one running windows xp, I can go to all the web sites and get the huge files list.
The second time I reinstalled, the same thing happened. However, this time I chroot'd using the livecd and emerge'd xfree and kde from there, hoping somehow that would fix it (remember, total noob here), but it didn't. I can't get to any web pages either.

Here's the basic setup of my computers:
Main computer (this one) running Windows XP with 2 NICs and basic internet sharing (since each student in the dorms is only allowed one ethernet jack/student) without windows basic firewall enabled. This PC is 192.168.0.1, and is set as the basic DHCP server. My second is 192.168.0.2. I can ping 192.168.0.1 from it, and vice versa. I copied resolv.conf exactly as it said, and upon inspection that file has the following in it:
nameserver 192.168.0.1
search mshome.net

The firewall here (at SDSU, San Diego State University) allows incoming connections, but no outgoing connections, except on port 80. So I can't ping any outside web sites, despite being able to go to the web sites in, say, internet explorer.

I'm at a loss as to what's wrong. I don't understand why it works off the LiveCD, but not once I reboot into the actual install. I also have no clue why it worked the first week I was here, but as soon as I had to reinstall it, it stopped working.