try this info

assuming you have sins 1.19/entrenchment 1.05/diplomacy 1.01,  the Mods NEED to be placed here for xp
C:\Documents and Settings\'user name'\Local Settings\Application Data\Ironclad Games\Sins of a Solar Empire\Mods-v1.19             (original sins)
C:\Documents and Settings\'user name'\Local Settings\Application Data\Ironclad Games\Sins of a Solar Empire\Mods-Entrenchment v1.05            (entrenchment)
C:\Documents and Settings\'user name'\Local Settings\Application Data\Ironclad Games\Sins of a Solar Empire\Mods-Diplomacy v1.01                 (diplomacy)  

or here for vista/windows 7
C:\Users\'user name'\AppData\Local\Ironclad Games\Sins of a Solar Empire\Mods-v1.19                     (original sins)
C:\Users\'user name'\AppData\Local\Ironclad Games\Sins of a Solar Empire\Mods-Entrenchment v1.05 (entrenchment)
C:\Users\'user name'\AppData\Local\Ironclad Games\Sins of a Solar Empire\Mods-Diplomacy v1.01      (diplomacy)

NOTE the first two folders after the 'user name' are hidden , so to see them you must first click on 'tools' then 'folder options', then 'view', then click on 'show hidden files& folders' then click ok, then you will be able to browse your want to the folder. I suggest when you find the folder that you create a shortcut to it on the desktop

NOTE 2 the 'user name' in the above paths is your WINDOWS login user name, eg Administrator

and if the mod you want to use is from an EARLIER sins/entrenchment version place the mod in the mods folder FOR THAT version eg mods-entrenchment v1.03, then download and run my mods updater from the latest version archive which will have the same number as the vanilla sins version number, and AFTER updating the mod(s) to the current version for any mods of pre 1.04 entrenchment ALSO run the manifest maker on ENTITY manifests on EACH of the mods EXCEPT for total conversion mods

harpo