I just did that. I removed my last dashboard widget a couple of weeks ago.
Open terminal and enter the two commands to change the default for dashboard and killall dock will restart the Dock which controls the Dashboard window.
Get rid of dashboard:
defaults write com.apple.dashboard mcx-disabled -boolean YES
If you ever want to put the Dashboard back:
defaults write com.apple.dashboard mcx-disabled -boolean NO
Message was edited by: bob wild