This gets rid of Ubisoft's annoying "must be online at all times" DRM. This will help anyone who's having problems playing the game thanks to Ubi's not so great servers.
1. Install the game from the DVD.
2. Download and install the 1.04 patch:
Mirror 1: http://www.megaupload.com/?d=OYUH6O9M
Mirror 2: http://www.4shared.com/file/7s4RlWS8/splinter_cell_conviction_104.html
3. Download the fix:
Mirror 1: http://www.megaupload.com/?d=WR64RFWY
Mirror 2: http://www.4shared.com/file/I2DRnlmT/Convictionv104-SKIDROW.html
4. Go to the game's install directory (usually C:\Program Files\Ubisoft\Tom Clancy's Splinter Cell Conviction\src\system)and copy everything from the zip into there. If anything asks to replace things click "yes" or "ok".
5. Now edit the Skidrow.ini, so that your username and password are there.
The game should now run without a worry of being kicked from your single player game.