Networking :: using DSL as a server/router/firewall

i recently acquired an old dell optiplex gxi (pentium 1, 64 meg ram, 4ish gig HD, woefully old BIOS) - it runs the HD bootable version of DSL marvellously - zero hitches.

i want to use this box as a server/router/firewall for a two desktop machines, one using win2k and the other winXP. chaining these machines is not an option because one or the other will be powered down at various points.

so what i want to do is configure DSL for three 10/100 ethernet cards - one taking input from a standard DSL modem, the other two connected to the windows machines.

i'm reasonable proficient in *nix OSes. any link/help/whatever is appreciated

original here.