If your adsl modem/router acts as your primary DHCP server, then you're basically set and only need an access point for the wireless. My basic setup at home is the Modem/Router plugged in with a straight thru cable into my 8 port switch. Then my Wireless AP plugs into the 8 port Switch and it all runs through the Modem/Router. The setup works and you can manage the AP and the Router through different pages. I feel that this is better than if you were setting up a multiple modem/router/wireless point.
However, just a tip - Make sure you enable WEP/WPA or WPA-SK protection and change default settings, along with a strong root password. These are for protection and also enforce MAC filtering. This will protect your AP from attacks.
Just another quick note - Make sure you turn off or disable your access point when you're not using it so that people wont try and crack your protection and use your ADSL.
:)