I'm Bi!
I use both...I need to get more familier with OS X because this will start becoming an issue in my district, and as the only "techie" in the Educational Technology department, I gotta get my feet wet.
I didn't start until a few weeks ago, because, frankly, I knew 10.0 needed some tweaking. (typical of any operating system...never jump in if the version ends in zero!)
So I've got one computer in front of me (G4 Tower with Cinema Display) runnin' OS 9 and the same configuration on a desk next to me runnin' OS 10.1.2.
I gotta admit, I'm very attracted to that OS X speed! And it's becoming almost second nature to jump from one to the other.
By the way, I downloaded Omni Web for OS X and it's BEAUTIFUL! I'm never opening up Explorer on the X machine again!
Scott