Connecting 2 internet connections through one server

[Mike Kelland <mike@mikekelland.com>]

Hi Everyone,

I'm trying to set up my server to masquerade 1 set of computers through
one connection to the internet and another set of computers through
another.  The specs are as follows: 

Server is a 600 MHz Celeron running a variety of things (email, Web, SSH,
etc...) and acting as a router for the house.  

Internet connections consist of a cable (set up with dhcp) internet
connection and an ADSL (pppoe) connection.  

The topology consists of 3 network cards in the server, each connected to
a different segment:
eth0 - Cable internet connection
eth1 - Connection to internal hub (all internal computers are set up with
static ips)
eth2/ppp0 - Connection to ADSL

The current setup consists of my computers being masq'd through eth0 and
eth2/ppp sitting idle.  The plan is to have my parents' computer be masq'd
through ppp0 while keeping mine the way they are.  Anyone have any
suggestions on how this might be accomplished? 

Thanks!
Mike