System Sounds in Windows 7 are designed to notify the user if something occurs. They can be useful, but sometimes annoying.
My demonstration used a bluetooth keyboard and Windows Media Player. Every time I pressed the enter key a "ding" would sound off. If done enough times the sounds can become very annoying. So sometimes it's better to disable them.
Now your system will not make any "ding" sounds when you press the enter key. Enjoy!