network design, need feedback…

Hey people, need some feedback on network design. See the pic below.

http://www.2shared.com/file/3528822/27929d90/network.html

Basically im in a debate as to whether i should put the firewall before the router or after it (like in the pic). I put the 1800 there to take the load of packet switching and multihoming off the firewall. keep in mind the 1800 is a firewall aswell but would just be firewalling the dmz (which is also debatable) and pretty much passing everything else down to the ASA.

I *believe* the design in the pic is what cisco recommends but there may be some natting issues to do with the multiple internet connections?

any thoughts appreciated. thanks in advance!