Old Athlon 2000 machine, need help with a free firewall, having problems with all i have tried

Ok I own three computers this is my oldest one which i keep at work to play with between customers.. Most modern firewalls eat up so much cpu it bogs the computer down to near useless.

Last week the motherboard died on it and i happened to have a spare Athlon motherboard in my spare parts boxes, so I rebuilt it and everything seemed fine.

I had used sygate personal firewall before since im not that terribly worried about its protection.(where i work is way out in the county, i only have dial up, and the best connection i ever get is about 32.2k.)

So when i reinstalled i did a little research and came up with comodo and online armor as two of the better free firewalls.

Online armor worked, but its resource usage would go into the 75-90 percent range when connected to the net, bogging the machine down to useless.

Comodo appeared to install just fine, but everytime i tried to dial out my entire computer would lock and i would have to force a hard reboot.

So i went back and installed sygate personal firewall, again it appears to install fine, shows its running in task manager, but if i try to open it to get to the options it just locks up.  If i try to get on the net, i cant, also because i think the firewall is locking up when it trys to pop open the window asking me whatever program im using is ok to go out on the net.

So for the moment I've turned on the windows firewall which of course is turning my stomach.

Suggestions/help getting any of these running without chewing up most of my cpu would be much appreciated, or suggestions on other firewalls to try.

Ty Much.