Well, learning Linux is a great way to get a head start on learning *NIX in general. If you are good with *NIX it's not hard at all to make $100k+(US) even in lower end markets. Now it's not good to have *only* Linux on your resume so if you hurry you can still download Solaris8 x86 and play with it. Experience is worth more than anything else so don't expect to jump right in and make $100k. Doing some Linux projects may get you in the door though and *most* shops that run Solaris, HP-UX, AIX, etc also run Linux (even if they do it in secret).
I happened to get my start as a mainframe programmer and took an interest in the old crappy 3B2 machine (which ran UNIX) but soon after we got some big IBM RS/6000 machines running AIX (IBM Unix) and because of my 3B2 experience I was asked if I wanted to head up administration on the RS/6000s. They didn't have to ask twice. From there I took some AIX classes although they were a waste of time as they didn't teach me anything I didn't already know.
Because of that experience I got another much higher paying job that happened to use Sparc/Solaris (Sun UNIX). Again I took a couple of Solaris classes which were again a waste of time as I had already learned everything taught in the class on my own. In both places I brought Linux in where it made sense to do so (starting early 1993).
I guess what I am trying to say is, there is not a huge difference between the various vendor versions of *NIX. They are all much the same at their base, sure there are differences but nothing hard to pick up if you know the basics. So if you try to learn as much as you can with Linux you'll have a great head start in becoming a *NIX systems person. You might look into RedHat training as they offer professional training, but only if you can get someone else to pay for it (your employer). For a start I would suggest getting some O'Reilly books on UNIX/Linux Systems Administration, TCP/IP, and Shell programming. These are the most basic things that will springboard you into other areas.
Oh yeah, a Computer Science degree helps in "some" places, however, when I hire people I could give a shit less about the degree or certifications. I've seen college edumicated and certifimicated people who are dumber than a box of rocks. If they can pass my technical interview then they have the job (some people leave crying after my technical intervew BTW.
I may ask you a simple question like "describe an inode").
Good luck!
[ March 21, 2002: Message edited by: VoidMain ]