Did you know that you can build and install OpenWRT on your WNDR3700? If you're not afraid to get your hands dirty building the firmware from scratch, then this tutorial is for you.
http://wiki.openwrt.org/inbox/netgear/wndr3700
The wiki contains instructions to prepare your OS for building OpenWRT from scratch, installing it on your router, and even a cable-free debricking guide for the WNDR3700.
Please post and let us know if you have tried this!
I have been using openwrt for awhile now. The only issue I am running into is their version of samba3 for file sharing is old and Windows 7 has issues with it.