Pix 501 & Linksys router question

I have a Linksys wireless router and a Cisco Pix 501 at home. What I want to do is have my cable modem connect to my pix and then connect my linksys to it so I can use the wireless. I have tried to run a cable to the linksys and it basically kills the hole network. I had to reload the pix and disconnect the wireless before i could go again. I’m not sitting infront of the equitment right now and I can’t remember settings that I have tried but what would be the best to get this set up and working?