Good Wireless Bridge To Use With Motorola 6580?

I'm running a Motorola Surfboard Extreme 6580 as my modem and main access point, but I have equipment downstairs in my home theater that I need LAN connections for. I want to set up another router/device as a wireless-n bridge to plug these into, and I don't want to spend more than necessary, but I want the best performance from my 6580. As the 6580 is only singal band, and my wife's computer only runs on 2.4ghz, I think I don't really need a dual band device, but a single band n device. I bought a netgear WNR2000v3 router, but when I try to bridge it (enable wireless repeating function) it tells me that I can not enable this function with AES, TKIP, or AES + TKIP enabled. The 6580 tells me I should use AES to get the best speed, and the WNR2000 won't let me use any security when bridging (the router's menu page hints tell me to enable WEP, but I don't even see an option for that, and it's pretty worthless as security I've been told). I think I need to return this WNR2000v3 and get something else.