Question about CyberGuard

["Gibson, Brian" <briang () multexsys com>]

 I have read several reviews of many of the commercial firewall products
but I have not seen any reviews or comments about CyberGuard here. Could
anyone tell me whether this is a solid product. I have been given the
task of implementing a firewall system for my company but I really am
just a beginner in the field of security or Unix for that matter.
 We decided to go with CyberGuard, although we are a mostly NT shop, we
felt that it was necessary to go a Unix box for a firewall. The trouble
is that we don't have a lot of Unix experience in the office and we
aren't likely to get any in the near future. Are there any known holes
with this system that I should know about?
 It is up to me to learn a lot more about Unix, specifically SCO, in a
very short time. Does anyone know of a good book to give a solid
fundamental understanding of Unix concepts? Not so much the commands but
the structure and conceptual design of a Unix system. I doubt I will be
able to get a SysAdmin course from my company so that option is not
available. Any help would be greatly appreciated.

 I realize that these questions are not truly on topic and perhaps this
post qualifies as noise but I felt that I would get a much more
qualified answer here than in a newsgroup for instance. Thanks for any
help.

 Brian Gibson