Need wireless access for clients.

I have Earthlink ADSL (static IP) with a ZyXel 643 DSL Modem/Router.

At the request of several clients, I have installed a Linksys Wireless Access Point in our office. They wish to be able to access the Internet while here. Since my network is set up for manual assignment of IP addresses and not DHCP, they would have to change their Network Connection settings each time that they are here. I want them to be able to connect using their current Network Connection settings - which are set to "Obtain an IP address / DNS Server address automatically".  I need to enable DHCP on the ZyXel 643 in order for this to happen - correct? Earthlink Tech Support first said that the Zyxel 643 wasn't configurable for DHCP Server use, but it is. Then they said that since my main Earthlink DSL connection is via a static IP, then I couldn't automatically assign IP's to machines on my network, which I seem to think is total BS.

At any rate, I generally need for my clients to be able to boot up their laptops while here, and hit the Net w/o having to change any settings...wardriving I guess...except legally. I DO realize the security implications with this type of setup.