You have all the files in C program files that holds all the game packs you downloaded. The one in documents is your personal game files for builds, sims and other items.
It sounds like you could clear out a few files. If you open Documents and check your Cashe file. It maybe very full then. It keeps a copy of items you saw and is of no use to you. So open the cashe file, click first item you see and scroll down to bottom of images and shift click the last image. This should highlight all of them and then you can delete them. I have had well over 1000 images in there sometimes. If you didn't know about this you probably have even more. This could free up some space!
If you have uploaded all your builds and sims and whatever else you may have created to the galley, you could delete the contents of the tray file also. If you have saved pictures to your library others have created, be careful not to delete them too. This could free up some more space.
If you have exception files in the documents folder they are of no use to you either. You get them for the gameplay not working right which happens way too often. I empty the cashe daily and exception files after I quit.
You can also try the suggestions for C program files.
