http://www.subsim.com/radioroom/showthread.php?t=96026
http://www.thegreywolves.com/
Download GWX 3 Gold. Read the manual, at least on installation.
Install SH3.
Install GWX.
Play and see if it works and whether what you see is to your liking.
If so, make yourself familiar with the sim.
Not before you have done that you should start investiong further time in checkling other additonal mods - and not all of them are meant to be run simultaneously even if they all are comptabile with GWX. So before you invest time in examining that, really spend some time and familiarize yourself with the sim+GWX, to see if it is worth it for you.
P.S. I had run it under W7x64.