Wireless authentication with DD-WRT, Cisco and Microsoft

I'm looking for a way to authenticate my wireless users beyond them just knowing the wireless password. Ideally they would join the access point then get dumped to the login portal that they'd have to log in with their current user name and password, which would get checked against AD.

Additionally, I'd be looking for two features: 1) That users could be "remembered" for 30 days (or some period of time) so they don't need to log in every time they want to use wireless 2) Somehow we could lock users out through some action in AD

My access points are Buffalo routers running DD-WRT. I have mostly Windows 7 machines and servers running Server 2008 r2. In addition I have a Cisco router and ASA firewall.

Can someone suggest a piece of software (or multiple pieces in combination) that can do this? From what I've Googled around this can't be done with my existing equipment but maybe I've haven't looked hard enough.