Network novice could use some help

First, thank you for taking the time to read this, I will be brief.

Short story, I work in a school with old computers, so I brought a rebuilt one in from home. The two tech people that work in the whole district have not returned a phone call in two weeks so I decided to try and get connected to the network and servers myself.

After a couple of hours I can now log on and connect to the server through my cpu and login name. I was able to find my printer and set that up as well. Two small problems are left.

Windows XP Pro Sp2

1. IE6 works and I can acess any website. FF2 can acess a few specific websites related to the school and nothing else. I get an error message that says the site is taking too long to respond, check to see if you are behind a firewall or if you typed the name correctly. Under my normal log in name (not connected to the server) I added firefox to the firewall acepted programs, but that did not fix anything. Under FF2 I was using auto detect connection settings and the switched it with the proxy address and same port listed with IE6 but that didn't help either. I can not turn the firewall off when connected to the network/server. If I just log onto the cpu and not the network I can not access the internet.

2. AVG 7.5 can not update, I did not really try and fix this one yet. I added some avg services to the allowable list but may have missed the right one.

Thanks for any help you can give

Switched FF to direct connect, didn't help.

I ran ip config but am not sure what to look for or how to change things from there. Should I be logged onto the cpu or to the server?

The IT guy told me about a month ago that there was no official policy about it, so thats why I decided to try it.

I had him install FF on my class computer because I liked it so I know it can work.

Oh well I've done what I can do. I guess I'm just stuck with IE6 and out of date virus definitions, everything else works