LINUX primer needed

If someone that is a LINUX Guru, would make a list of LINUX commands and
there equivalent in DOS, it might help a lot of us out in the learning curve.
I see some commands that are very strange to me, and some that look similar
to DOS commands.
I feel that a lot of the problems with the LINUX install is related to the
video board. Is there a low priced board on the market that would solve
these problems? In my case I really don't know for sure what the video board
characteristics are for sure, and that brought me to my knees, when
installing the Xthingie. LINUX (Red Hat 5.2) actually installed easily, but
that was the end of it so far. Shop temperature almost 90 degrees today.
bill