Networking another PC through another...

Here's what I'd like to do. I have my main PC which is connected wirelessly
to my broadband router. It is also fitted with a normal NIC.

I'd like to connect one of my machines through this PC so that it's able to
connect it to the internet. What's the best way of doing this? The main
machine runs XP Pro and the PCs I'd like to connect periodically through it
run Win2k and Mandrake 9.2.

Is the Linux machine going to be problematic? I was going to try doing it
with the 2k machine with ICS but that then started changing my pre-set IPs
and I ran out of patience! Just thought I'd ask people's opinions before
beginning to fiddle again.

Thanks
Ste
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