Here's a super great tip I learned from an article at Lifehacker.

My laptop here at work, a Lenovo ThinkPad, has a tremendously loud beep (through headphones, it will nearly blow your ears out). This beep occurs every so often when I'm typing faster than the computer thinks I should, and I end up pressing several keys on the keyboard at once. Thankfully, there's now a way to disable this annoying sound!

To temporarily disable the beep: net stop beep To permanently disable the beep: sc config beep start= disabled

In the latter command, note the space between the equals and the word 'disabled.' I'm not sure if that's necessary or not, but including it worked for me. The space is indeed required (thanks Dustin). I had no idea that a Windows service was responsible for this annoyance!