We use Debian on 12 servers and it runs our organisation. Debian is stable, free and well supported. We run in-house email, intranet, CCTV, file sharing and all the usual office/support systems. Debian is the only logical choice, and I trust those involved not to steal my information or compromise our systems. We have saved many tens of thousands of pounds through this choice and given our users very good uptimes and reliability to boot.