assuming you have sins 1.16 & entrenchment 1.02 then the correct folder for xp is
C:\Documents and Settings\'user name'\Local Settings\Application Data\Ironclad Games\Sins of a Solar Empire\GalaxyForge
and for vista/win7 it is
C:\Users\'user name'\AppData\Local\Ironclad Games\Sins of a Solar Empire\GalaxyForge
(note the two folders after the user name ARE hidden so you MUST unhide hidden folders in the folders options)

for sins 1.15/entrenchment 1.01 then you want my galaxy manifest manager which is included in my sins map updater v1.1.8 which also converst version 2 maps to version 3 to use in sins 1.15+

hope this helps

harpo