What happens if I delete the registry key?
A fog-enshrouded portal will open up in front of you, and you will be forced to pass through it into a hellscape called "RegEdit BooBoo". Abandon all hope. Do not turn off or reboot your computer. Run away, run away!
Seriously though, you'll probably break something important, and you might not be able to fix what you broke. Deleting system-critical registry keys is a great way to refresh your memory of how to re-install Windows from scratch.