I know this subject is controversial, but here’s what I have found in 25 years of experience. I use Windows, Linux, Unix, OpenVMS, FreeBSD and other operating systems all day long, and I am experienced with IIS and Apache. My conclusions are based upon actual testing and benchmarking, not rumor and articles by others.Stick with the brand names for mission critical systems. Open source is fine for many things, but excluding the “big products” such as Mozilla, Apache and so forth, I am leery of it.I would never even consider open source for the important things such as payroll, general ledger, accounting, warehouse operations and SCADA. These are the applications which companies actually use and need to stay in business.I have never found anything that even approaches Office XP feature-for-feature. Office XP is rock solid, doesn’t crash and is very secure. I cannot say the same for Staroffice, Wordperfect and the other competitors.Windows 2000 and Windows XP are unmatched in quality as far as their market is concerned. Windows 2000 server is rock solid stable, has an incredible number of features and, most important of all, is supported and well documented.Windows 2000 also has a security model which is unmatched in the industry. This model came from the VAX (Digital Equipment) and Novell, both of which were (and are) excellent. Linux and Unix don’t really have a security model in comparison (I am referring, of course, to active directory and NTFS).Of course, Windows has the well known issue of security exploits (a different issue than the security model). I currently manage quite an extensive farm of IIS servers, and I’ve found it’s not that much work to keep these systems completely up-to-date. We just have to do our jobs as administrators.