The big question is: should I go with Slackware or
GenToo Linux as my
 OS? 
IMO: no.  (Well, you did ask.)
  I know some are suggesting NetBSD, but I'm looking
to make this thing
 easy enough so my gf can tinker with it [...] 
I'm not convinced that adminning one Unix (Linux) is really that
different from adminning a different Unix (NetBSD) to someone not
accumstomed to either.  (Admittedly, I'm _not_ "someone not accumstomed
to either", so I'm not really as competent to speak on the subject as I
might like.)
Unless you have some definite reason to think that Linux would be
easier for her to tinker with than NetBSD, I don't really see any
reason to reject it out of hand.
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