I know that Arbor Networks is a company working on the DoS
problem. I don't know if their software is proven (or is finished)
but I do know they have some serious genius level security/
network hackers working on the system. You might want to drop
them a note to see what they offer, if DoS is your greatest
concern.
http://www.arbor.net
(note, i am not affiliated with arbor networks in any way)
