I am soon to have 2 separate internet connections in my home (one cable and one adsl). What I am wondering is if my 2 main macs can use separate internet connections and still have a local LAN together.

I would assume I need 2 ethernet on each system. My only option then would be to use airport and ethernet on my mini then add an ether. PCI card to my Sawtooth G4.

As far as I know a router can only use 1 connection. Any advice or help is greatly appreciated.
Mac mini C2D 1.83GHz - 2GB RAM - 200GB 7200rpm HD
Sawtooth w/G4 1GHz - 1GB RAM - SIIG SATA w/2x1TB HD
B&W w/G4 600MHz - 1GB RAM - 2x80GB HD
Sawtooth G4 400MHz - 512MB RAM - 40GB HD
Dell Ultrasharp 2007WFP 20" Widescreen LCD
2.94TB Total Storage