linux firewall or SUSE

My son is having problems with his ( XP ) PC. He seems to be getting smurf attacks, or something like that. I'm not sure I can sway him to run SUSE ( or any Linux distro), but I may be able to get him to run a Linux firewall on another, older, spare PC. Could he just run SUSE on this spare box and use his cablemodem from XP, through the SUSE box? what would be other suggestions for a Linux firewall box ? -- Paul Cartwright Registered Linux user # 367800 X-Request-PGP: http://home.comcast.net/~p.cartwright/wsb/key.asc