Grant has mentioned this link: http://forums.cncnz.com/topic/13529-the-tiberian-sun-installation-pack/ which will take you here to download the best installer out there http://cnc-comm.com/community/index.php?action=downloads;sa=view;down=41
Handy Links. (New Tiberian Sun Forum Users/Players Look Here)
Tiberian Sun Ports
Where to download Tiberian Sun?
There are three versions of Tiberian Sun you can download. A version from the official C&C site (which is not recommended due to a few bugs)
The following versions are recommended:
Tiberian Sun MultiPlayer Only (Created by Olaf van der Spek) http://xwis.net/downloads/Tiberian-Sun-Multiplayer.exe
It has Skirmish and Internet Play only. (No missions)
The next version isn't officially supported by XWIS. It includes missions and online play. http://forums.cncnz.com/index.php?showtopic=13529
However a LAN patch which conflicts with online play on XWIS is default in the install. To use this version with online games remove (or move out of the folder) a file from the game directory called wsock32.dll. http://xwis.net/forums/index.php?showtopic=154971
ST staff do something. It has been brought up on support forum already http://xwis.net/forums/index.php/topic/179797-tiberian-sun-installer/ and not the first time...