A discussion about translation services, translators, and translation software

This post is the initial entry in the category of Translation Software.  Let's pretend that I'm the Rip Van Winkle of translation and that I just woke up from a 25-year nap.  When I went to sleep, translation was done by clever people with dictionaries.  Now, translation is done by clever people with dictionaries and computers!  And the clever people get help from their computers using stuff called software for computer-assisted translation (CAT) or machine-assisted translation (MAT).  Well, I never!

The truth is that I'm a freelancer who has just left nearly 25 years of government work, including translation, that didn't involve the latest and greatest technologies.  I'm still using dictionaries.  I know that I can find reviews of popular CAT software online, and I'll do that, but I need input from users and agencies to tell me the ins and outs, pros and cons, frustrations and blessings of CAT.

My first questions are these:  What's the learning curve?  After I pay the hundreds of dollars, how long will it take until the computer and I are translating together smoothly?  What will it take to make me feel that I have invested my money well?  And let's get ruthless.  Why is one CAT "tool" better than another?  I accept biases and blatant product pumping.  If you're a SYSTRAN junkie (or salesman), or if you favor some other program, I offer you a place to tell it straight.  I've been to the sites, and the sales pitches go over my head.  After all, I just woke up from a long nap.  I'm a blank slate.  Brief me.