Where and How
So where should you keep back ups of your beloved families and downloads? If you have a CD or DVD rewritable drive, I strongly suggest you copy your files to a CD or DVD. If not, you should copy the files to another drive.
Which Files
Now here's the biggie. Exactly which files should you be backing up. Anything that involves your families and downloads! So where are these files hiding? Below is a list of folder locations and the type of files you can find there. You'll need the subfolders also!
Object Downloads
C:\Program Files\Maxis\The Sims\Downloads
and/or
C:\Program Files\Maxis\The Sims\GameData\UserObjects
Floors
C:\Program Files\Maxis\The Sims\GameData\Floors
Roofs
C:\Program Files\Maxis\The Sims\GameData\Roofs
Skins
C:\Program Files\Maxis\The Sims\GameData\Skins
C:\Program Files\Maxis\The Sims\ExpansionShared\SkinsBuy (if you put custom skins here)
Wallpaper
C:\Program Files\Maxis\The Sims\GameData\Walls
Neighborhoods
Copy all UserData folders - Numbers represent neighborhood number
C:\Program Files\Maxis\The Sims\UserData##
Zip Files of Downloads
Remember to backup the folder(s) that have downloaded your files, especially the ones you haven't installed yet.
