Question : Problem: DSL VPN Tunneling without static IP's

I have a friend who wants a network set up. He has an office (main location), another office (remote location) that needs access to the main office, and he wants to connect from home to the main office. He wants it to be secure, so I figured a VPN would be best suited. I picked up 3 Linksys WRV54G dsl routers than can do VPN tunnels and VPN client access. I configured them with 3 local networks 192.168.161.0 (main office), 192.168.162.0 (second office), and 192.168.163.0 (home). All three have different DSL providers and modems, none of which have static IP address'  In this scenario, how do you config the VPN tunnels? Initially I set them up as routers with DHCP set to get the IP from the DSL provider, didn't work at all. Changed 1 to gateway instead and it allowed the site access the internet,didn't try a second one to connect to that one. In the configuration page you put the local network, the remote network, and the remote gateway addresses. Is the remote gateway address the ISP address that the DHCP picked up? If so, when the DSL bounces for some reason, you would have to manually have someone change it on both ends .... help

Answer : Problem: DSL VPN Tunneling without static IP's

First you need to set these up in a typical fashion as routers to allow basic Internet services. The WAN/Internet connection may well be dynamic connections, that is determined by the ISP.
In order to connect using the VPN you need to know the IP of the router at the time of the connection. As you pointed out, if you have a dynamic IP, this keeps changing. To resolve this you need to subscribe to a free DDNS service (Dynamic Domain Name Service).  With the DDNS service you add the assigned domain name, user name, and IP address to the router's DDNS configuration page, it then notifies the DDNS service every time the IP changes. The DDNS service tracks the IP changes and associates them with your assigned domain name. The end result is you connect to the name rather than the changing IP. I would recomend using www.dyndns.com  If you would like more details on setting up the DDNS service I just posted detail instructions here:
http://www.experts-exchange.com/Hardware/Routers/Q_21781969.html

Note: I would update the router's firmware before doing any of this. It often heads of some potential problems the manufacturer may already be aware of.

Once all of this is in place you can configure the VPN. See the following link for the Linksys RV042. The VPN configuration is almost the same as the WRV54G, and these instructions are for using DDNS names rather than IP's, as you are about to do:
http://linksys.custhelp.com/cgi-bin/linksys.cfg/php/enduser/std_adp.php?p_faqid=1704&p_created=1094687101&p_sid=U6Top31i&p_accessibility=0&p_lva=&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9MTAzJnBfcHJvZHM9MCZwX2NhdHM9JnBfcHY9JnBfY3Y9JnBfc2VhcmNoX3R5cGU9YW5zd2Vycy5zZWFyY2hfbmwmcF9zY2ZfbGFuZz0xJnBfcGFnZT0xJnBfc2VhcmNoX3RleHQ9cnYwODI*&p_li=&p_topview=1