Welcome to the wonderful world of SH3!
While I can only speak for myself, I would definitely recommend going with the Grey Wolves (aka GWX3) supermod. It adds so much in the way of graphic and gameplay enhancements as to be virtually light years ahead of the stock game.
Once you've got GWX,
http://www.thegreywolves.com/downloads/ there are a number of great additions - many of which can be previewed right here:
http://www.subsim.com/radioroom/showthread.php?t=170090
However you decide to mod it, I'm sure you'll find your free copy of SH3 to be a real treasure in a sea of average games. Once again, welcome to the pack and good hunting!
