Using router as access point

Going to a client which has Simens ADSL wireless router. Now, He has a BIG apartment, And I'm afraid that in some parts of it I won't have good enough signal to connect his new laptop.
I thought taking my new TP-Link wr541G router as a "plan b" and connect it wirelessly as an access point via mac addresses security.
Do I need to disable DHCP in one of the routers ? Are there other things (Except security) that I need to take into consideration ?

Disable the dhcp and the security in the one that you want to use as an access point.
The manual should also tell you what else to do
http://www.tp-link.com/english/soft/200865135820.pdf

Thanks Ferrit. I used to WDS 2 3com routers and disable dhcp on both, And applying static ip addresses on clients, This time will try to disable DHCP on the "access point" after giving it static address out of the DHCP address pool and see how it goes.