I've not used mods before and when I tried to install one I had no luck. I created the folder in XP:

C:\Documents and Settings\Administrator\Local Settings\Application Data\Ironclad Games\Sins of a Solar Empire\Mods                (I log  on as Adminstrator)

 I then duplicated the folder in the All Users and Default folders. The game setup mods option says it is looking in the Adminstror folder.

and put the mod files and folders into it as instructed, but the Mod never comes up as an option in the game setup. The mod in question is CapShips 1.3.

Also, I have seen this same mod installation question more than once over the last months but the answer to it does not come up in a search nor is it ins the FAQ/stickies of the General, Technical of Modding forums. This should be corrected.