I hear ya with the space making!
Here's what I've found-
EAW and OP- I deleted the music zip files no probs. I haven't tried any other sound files, just because I rather think I need them lol. However, you can delete the movie files (all 3 versions) with no trouble- they're pretty big too. I've found I can't delete the sound files in #3- wish I could, but it won't work!
To experiment, try removing the sound file from its parent folder to the desktop. Run the game, if it works, then you can delete it
If not, put it back where it came from.
On a further note, try a junk file remover application. You won't believe how junk accumulates! I recommend HDValet- I've had no troubles with it. You'll have to search a bit for it, but it's worth the trouble.
Good luck Ron!