Use DSL Modem/Wireless Router as a dumb wireless router
I think all you'd need to do is disable the DHCP server on your ActionTec modem and assign an IP address in the same subnet as your ISP modem to the ActionTec (Ensure that it's not in the DHCP range of your ISP modem).
In your current configuration, you have two DHCP servers in your network and your ActionTec will send a DHCP offer with the its IP as the default gateway which is not what you want. Once you disable the DHCP server on the ActionTec, your ISP modem will give out IPs correctly to all devices and your ActionTec will perform only as a wireless access point.