I'm confused... You mention two boxes 192.168.0.1 & 192.168.0.2. Then you say about a (another?) dual boot box with a modem. Thats cool three boxes... Then you say "...see the internet from the server..." but which box is the server? I take it that its not the machine with the modem? Some more info please!
If you are trying to share a modem connection then you want to look at http://www.tldp.org/HOWTO/IP-Masquer...WTO/index.html
. If you are going to run Squid and fetchmail then I assume you are doing to do this on the machine with the modem anyway, is this correct or am I misunderstanding?