I don't know if www.prioritycolo.comspecializes in fighting off DDoS attacks, but I can tell you that when I was heavily DDoSed 5 years ago, Myles et al handled it very efficiently. I have been with them for 6 years now and have nothing but accolades for them. They allow me to focus on growing my business, rather than having to worry about the server, ever.
BTW, in case you did not make the connection, I am referring to WHT username porcupine (who has posted in this thread).
Good luck in your search.
DemoDemo.com - Flash tutorials since 2002 DemoWolf.com - 5,300+ Flash tutorials for hosting companies, incl. Voice tutorials