Will this Work?
Modem----ethernet--->Extreme----Wireless----->Express-----Wireless----->Express
\Extending/ \Extending/
Will the last express extend the already extending one?
This configuration can work, but it would have to be configured as a Wireless Distribution System (WDS) and not as an 'extended' network. The reason is because the 802.11n version of an extended network works more like a wheel. That is, the extended base station would be at the hub of this wheel and each extending base station would be on a spoke of that wheel. What you appear to want is a linear combination of base stations and this was only available in the older 802.11g WDS network.
Unfortunately, a WDS network has two major disadvantages: 1) It can only operate in the 802.11g mode which would, effectively, negate the advantage of your 802.11n base stations, and 2) For each base station added in a WDS, the overall wireless bandwidth (speed) would be cut in half.
Another option would be if your home is pre-wired for Ethernet, you could configure a roaming network which would be superior to both.
