Please help - Strange issue

I have been using a Linksys router with a cable modem for some time now. I
use Remote Desktop and PcAnywhere to connect to my PC when I'm in a
different location without any problems. I recently bought a ZyXel (Zywall
2 ) Firewall/router. Now, I cannot connect from outside my LAN using Remote
Desktop or PcAnywhere. I have forwarded the appropriate ports (TCP 3389,
5631, etc.). Now the strange part: My WAN ip address always starts with 24
with the Zywall; however, my WAN ip address always started around 66 - 68
with the Linksys. Just to see, I hooked the old Linksys back up today, and
my WAN ip address started with 66 like always. I hook the Zywall back up and
the WAN ip address starts with 24.

Please help,

Thanks

Kevin