RedHat is good... lots of people use RedHat, and lots of things are based on RedHat; but make sure you learn BSD too, as there are quite a few places out there that use true unix.
MySQL would be the big database program.
Apache is THE web server. Period. Don't let MS fool you into thinking otherwise, and the best part about Apache is that it runs right out of the box (so to speak).
Web scripting: Everything under the sun that you can learn, you should learn. One week someone wants a php developer, next week it's ASP, the day after it's perl (using mod_perl).
My personal opinion on JSP; it's more efficient to write the servlet myself.
Then again, I am one of the unemployed, and haven't been having a hell of a lot of success trying to change that, but I also don't have the "real world" experience that it sounds like you have, so take my advice with a grain of salt.
cheers!
starX
www.axisoftime.com
