I'm basically using Knoppix for the following reasons:
(1) Includes SGI's 64 bit Journaling file system. Probably the best file system in the planet.
(2) A reasonably latest 2.4.x kernel. Not to mention that ClusterKnoppix has "Mosix" compiled in the kernel, which makes parallel processing a piece of cake.
(3) Boots off CD, and runs full graphical, detecting all sound, video, network cards, etc., peripherals. So if someone wants to "try" Linux before installing it on the Hard Disk, the can do just that.
(4) Almost all pre-configured applications run

( other distros have many broken links)
(5) The new APT-GET is a breeze, to keep dependancies. Just apt-get install "your favorite package here", and all binaries are downloaded and installed/updated. No more RPM (Nightmare!) crap, full of broken dependency maintenance.
And to add to this, the new kernel 2.6.x just released (but still experimental), now supports up to 32 processors.
So that will give a run for their money to some high end propietary computers

I've been an applications developer/integrator (Using *BSDs) since 1994, and now after seeing the things that the Linux kernel offers, makes me think twice about which platform to choose

Before, I would go 100% every time with BSDs. Now, well, I think the writing is very clear on the wall
-kwag