Actually, if you set the -noborder launch command in tf2, this would be possible (assuming noborder works for dual displays). However this presents the issue of decreased performance.
"Just because nobody complains doesn't mean all parachutes are perfect." --Benny Hill
I do. Just not for TF2. Cause then I'd be wasting cpu cycles on a reverse-engineered implementation of windows code. I used to do this but I've changed my ways.
Anyway, I still use linux on my laptop for schoolwork. In fact, I just figured out how to get the software I need to use in a class to run on Linux. I made a tutorial about it @ http://rpi.edu/~langdg/litec-linux.html
"Just because nobody complains doesn't mean all parachutes are perfect." --Benny Hill