It's pronounced "touchy"
As has been pretty-well documented, I don't much care for those "I'm aMac" commercials. The new ones are no exception. Like this one. "Hello, I'm a Mac." "And I'm a PC." "And I'm a PC, too." This is the one where Mac chastizes PC for not using "touche" correctly.
"Yeah, see, now you can run Mac OS10 or Windows on a Mac, so in a way I'm kinda like the only computer you'll ever need."
"No, I don't think you're using that right."
"No, listen, see, you can only say 'touche' if you make a point and then I make a counterpoint, you see? So I said I run Windows but you haven't made a point yet."
This lecture is entirely incorrect. PC's point was that he's a PC. Mac's counterpoint is that he's a PC, too, BECAUSE he runs Windows. That he runs Windows is not by itself a new point. Ergo, PC's use of touche is correct.