As much as I want to ditch Windows altogether (I’m currently writing this on a dual-booting laptop with Windows 2000 and Gentoo Linux), I find even for me the critical apps aren’t there for linux… yet. I don’t doubt they will come. Once a few businesses and governments take the plunge and switch, the companies that make these critical applications will suddenly realize there is a huge market for their products (even in an arena dominated by Open Source). Open source can do a lot, but things like accounting software (Quicken) and imaging (Photoshop/Paint Shop Pro), etc. still on have Windows (and/or Mac) offerings. But do believe in the next five years, you will see these major programs ported to Linux.