In my personal experience, I've gotten much better results with a
router/router table.The dado (if you even have a stack of dado blades)
is quick and once set up (kind of a pain), pretty easy to use. They can
be kind of dangerous for the uninitiated.
If you're comfortable with the router, just do two passes (with a 1/2"
bit) to cut both sides of the dado. Use a up-cut spiral bit to pull
chips away from the cut, so it won't clog during the first pass.
Otherwise, go real slow. Use lots of hold downs, guards and dust
collection. If I were going to do this, I'd measure the dado and make
the first pass to cut the dado wall closest to the fence *twirls finger
trying to imagine bit rotation so as not to sound like a dork* and the
farthest wall/pass, second.
I hope this helps,