Just be smart, 2 years ago I planned to make a cluster inside a web compagny, And we planned to used Linux and a lot of open packages, that can be updated within the hours, if we encounter some DDOS... We also make this web cluster redundant, so if a web server is potentially weak under any kind of attack, we drop-it (and changing version of apache or whatever) and nobody heard about a down time ! Still interested to heard a MicroSoft Tech sing the same song, I don't think so !