I've seen several posts on converting an old computer into a firewall router.
Slowly and finally, I have accumulated enough for the project.
I am not savy to the nuts and bolts of Linux. I like some of the boot from cd distros, but when editing for hardware drivers comes up, I'm lost---not enough time to learn

.
I found an older p 166 computer at an auction. My bid of $2.50 was the only one

. It had a clean(no virus) win98se on it( it was a municipal comp and was not used online)
It needed a cpu fan.... another $2.50
It booted properly,even had Norton Enterprise AV .
I installed a second ethernet card from my junk collection.
I was going to use ICop, but neither of my ethernet cards were on the ICop list, and weren't recognized when I tried the instal.
But, being the forward thinking guy I am

I had bought, several years ago, Sygate 3.0(by Acer) which is an internet sharing app for just my purpose.
Sygate seems to no longer sell this software. But it had good reviews.
I bought it for about $10
It runs under Windows, so I'm comfortable with it.
Sygate also hides the fact that it is sharing the connection with other computers.
If a hacker did get in, hopefully, all he/she sees is an old slow mostly empty box.
To divide the connection to other computers in my home, I recently bought a Linksys network switch for $10.
Sygate has the option to not just hide the sharing, but also firewall the box. But, numerous ports would have been left open and I didn't like that. So I installed an old Norton 2000 firewall that I know how to configure pretty well.
The Host(Sygate comp that does the sharing) saw my three comps immediately, one win98se and 2 XP Home. The XP boxes recognized the Host automatically and Winipconfig did the 'magic' for the win98se box.
Now, I know a Linux firewall would have been cheaper, and maybe even better, but only for someone that is comfortable with it--I'm not.
So, I spent about $25 on the project and am very pleased

A bonus is that this Host(Firewall) can be used in a normal fashon, on line even, so if some one wanted to do some prime number 'chasing' or lend computer time to a project like cancer research, this setup will do it with out affecting the network accessing the internet~~~sweet deal