Wireless Router Action Tec Mac Core DUo

Hello! I just bought a brand new iMac Intel-Based Core Duo and cannot connect to my wireless router. I have found other info about this problem but nothing that describes an answer.

I can connect to the wireless router with an iBook and also a Windows laptop but am unable to connect via my new iMac. The message "there was an error joining the airport network "ACTIONTEC"" appears after I try to connect and enter the password for the router.

The wireless router is by Actiontec through Qwest. Any help would be greatly appreciated. If you have been able to fix this in the past please let me know what the solution was! Thank you!