2 routers 1 connetion problem

I've 1 ADSL modem (zyxel 650ME) wich is connected to internet.
This ADSL modem is also a DHCP server and may serve up to 4 addresses.
It's default IP configuration is 192.168.1.1
It uses PPOe mode.

I've just bought a LinkSys Wireless router. It has 4 ethernet ports and
wireless access.
It's default IP configuration is also 192.168.1.1
this router has off course DHCP server enabled and may serve many more
connections, so I'm not limited to 4 addresses anymore.

What I'm tring to do is configure the linksys as a DHCP server, wich does
serve all my computers's addresses and not to use the modem DHCP feature.
Problem is that I don't know how to set the modem later as it doesn't have
any IP. I don't want 2 subnets, all computers must be visible.

How to do so ? I'm quite a newbie in such networking stuffs.

Bob