Extending range of Airport Extreme Network

[maco]

AirPort Express frequently asked questions (FAQ)
http://support.apple.com/kb/HT1515?viewlocale=en_US#2.5

Using the AirPort Admin Utility to create a WDS network with multiple base stations
http://support.apple.com/kb/HT2044?viewlocale=en_US

I use an AirPort Extreme, an AirPort "snow dome" & AirPort Express. Works well for me.