It sounds like you're as much of a Ubuntu evangelist as I am a calibre evangelist.
Actually, it'll probably be on the next computer I build. And if my mission-critical programs (other than calibre, I mean!) run under WINE, it'll be on the one after that, too. And then there's the computer I have to build for my better half, who's been using Linspire (shudder) for a while ... that's getting Ubuntu. And maybe I'll replace that mutant Xandros on my ASUS netbook with something that, um, works. Like the netbook-specific Ubuntu.
So yeah, even us Windows users have our preferences in Linux.
Let the distro wars begin!