Need Best (fastest speed) Setup help....

I currently have a WNDR3700 that I'm moving to another end of my house as I'm moving my office... I would like to maintain good connectivity to both wired and wireless connections from where I'm moving my wireless router from and where I'm moving it too. I do have the ability to run a Cat5 cable between the two locations as I would like to maintain GigE wire connections to my media center extender (xbox) and other devices located there...

The ideal solution would be to link another router or extender to my existing WNDR3700 via an Ethernet wired connection and have that router/extender also broadcast the same wireless access point (same name) including dual band (2.4 and 5 ghz) support. Then this router/extender would also allow for additional GigE devices to connect for fast network speeds via the wired connection to my new office where my home server is...

I've looked at the WN2500RP but I don't believe that to allow for Gig-E connections needed between my Xbox and my home server... I would not be apposed to get a second WNDR3700 or maybe an newer model if needed but can the network repeating work be done over a wired connection?

Any help on what to purchase would be appreciated...

Other stuff I'm using:
NetGear 8-port GigE switch: GS108 (connected to WNDR3700)
Motorola surfboard cable modem: SB6120 (plugged into my WNDR3700)

Doug...