I'll go again -
IMax Extreme has the least amount of weights - it's only the compound exercises from C&W - weight wise. But it's a fun cardio workout.
Viper has the most intense weight work - and will give you more of an upper and lower body workout.
Gauntlet is inbetween - with an IMax 2 blast followed by BC lower, C&W Compound, BC Upper and a BC Cardio Blast. I think Gauntlet is actually the most intense of all of these (and the most fun). But that's me.
It's a great DVD - I highly recommend it.