ESPN has an automatic one:

http://espn.go.com/nba/playoffs/predictions

Based off my results on the first attempt I think it's pretty much junk:

48

In this case a 12%, 16%, 19% (finals which you cannot see in picture) and %34 chance of upsets all happened for one team.

Jesus, that thing is all kinds of fucked. The Hawks have a 12% chance of beating the Bulls? The same odds it gives the Pacers?