Probably quite a few... they might not like it, but many are still forced to use it because of their work...

I use outlook 2003, and I think it sucks (about as politely as I can put it), but I have to use it at work.

I live in the Bay Area, but SF is a little to far for a usability study - if you set one up closer to San Jose, I'd be interested in helping out.

Personally, I haven't used Outlook since 2001. That's when I switched to a Mac. Then in 2004 I switched to Gmail. I dislike thick mail clients.

I use outlook against my will. You know employers often are unreasonable :(

Bad luck I'm on the other side of the world to come to SF!