Network topology: Internet connected on a leaf node?

Before I go ahead and spend money on new kit, I'd like to run by you my proposed network setup to see if it's feasible:

Cable Modem <--> Airport Express <--> Airport Extreme (bridge mode) | +------> Clients +------> Another Airport Express ----> Clients

The Expresses extend the wireless network from the Extreme.

The reason for connecting the Cable Modem to the Express is because of it's location in the house. The Extreme is centrally located, and does a good job today, but I'm moving from ADSL to Cable, and that will be connected on the edge of the house rather than to the Extreme like it currently is.

a) Would this topology work? Would the Extreme route traffic through the Express to the internet? b) Are there any problems in this approach that you can envision?