How to get file & internet sharing over Firewire?

Hey all,
I'm headed to college in a few weeks; I'll be bringing my laptop and my desktop. I'm going to network them using Firewire (cheapest option); school doesn't allow routers/switches/etc (retarded policy, but you lose net access if you violate it), so my options are limited.

Anyway, I really only need file-sharing...which is easy to get. I assigned the PC to 192.168.1.1 and the laptop to 192.168.1.2...subnet mask 255.255.255.0. That works great for file-sharing. Which is all I *really* need for college, as the PC will get internet through wired ethernet, and the laptop will get it through wireless...so I don't need to share internet at school.

HOWEVER, I would like to get internet sharing going too, b/c I dont' have an ethernet cable long enough to connect my laptop (last long cable went to connect my desktop to the router).

So I've found that the only way to make that work is to bridge the ethernet/firewire connections on my PC. Then set both PC and laptop to "obtain IP automatically." This results in functional file-sharing...BUT the internet only lasts for 10 minutes before cutting out. The only way to restore it is to unplug/replug the cable.

I've tried setting static IP addresses, but that hasn't helped...unless I was doing it incorrectly?

Please help,
-Eric