Personally I use mechanical keyboards and will never go back to a rubber membrane keyboard again (all Logitechs are rubber membrane keyboards as are the majority of consumer keyboards).
Many of the mechanical models are loud but there are some that use soft key switches as well.
Refer to these:
http://www.overclock.net/keyboards/4...ard-guide.html
http://hardforum.com/showthread.php?t=1468692 (goto the end of this thread for latest info)