Personal Firewall Software

greetings!
I have a quick question that's quickly going to escalate into a complicated one. I have a laptop that I'm soong going to be taking in to school for use during class, and there is every chance that I'm also going to be connecting to the school network. (that is, I'm in the IT department and connecting to THEIR network.) I don't feel particularly comfortable about doing this without a personal firewall, but I'm not sure what to use because in all honesty I've never needed one before. what do you suggest I use, when my computer has the following specs:
AMD K6(2) 475Mhz
192MB RAM
Windows XP with SP2
Symantec Antivirus Corporate v10.0.0.2.2000

also, price of the program is irrelevant, so feel free to suggest expensive ones as well as free ones.
thanks for your help.

p.s. if you suggest I use Windows Firewall, I will carve into your head with a spoon and eat your brains with it, because you don't deserve to have those brains. not that there'd be much there....

Zone Alarm is fine, but I'd be more concerned with being on an unencrypted wireless network. Nobody's gonna haxor your laptop in class, but they might sniff your passwords or just spy on your online activity. If your school offers VPN you should look into using that.

Seriously, all firewalls pretty much do the same thing. Zone Alarm is good if you want a simple interface, and BlackICE is good if you want a complicated interface. Try out a couple and use the one that you like the most. You probably won't get a lot of quality help from a message board on the Internet as far as this goes.