Welcome!
you can get the patch of the official site below
http://silenthunteriii.com/uk/updates.php
This is the UK/MIDDLE EAST/ASIA patch be sure to switch the site to the US one if you use the US version.
If your useing steam it "should" already be patched up to the latest build.
You are in for a real treat with GWX..
makes the stock game like a day on the lake in a dingy
Enjoy my friend