I currently have a D-Link DSL G-604T Router/modem at thome. This is connected to my mediacentre, laptop (both wired and wi-fi) and xbox 360. The laptop has a Intel(R) Wireless WiFi Link 4965AGN card but only 10/100 lan while the mediacentre has a gigabit lan connection. I would like to speed up file tranfers (mainly video) between the 2 and also perhaps share an external HDD.
I have looked at an Apple Airport extreme as a possible solution. That does not offer ADSL connection so my question is can I connect the DSL 604T to the airport and access the net through it. This might also give me the advantage of using the airport in 5GHz setting for N only and the D-Link in 2.4GHz b/g. Would this work? I imagine the setup would be something like in the pic (apologies for the poor drawing skills)

If this will work is there any special setup required?