I do. It's really nice on a Mac. I was able to set it for just my account, and it's always on once I log in.
On Windows, you have to go into preferences, but then you can enable it with alt-shift. The problem is that you have to enable it for each application, although if you have multiple instances of an application open, they all use it until you completely close the app (Word, Excel, etc).
Dvorak also discourages anyone from using your machine.