I'm not sure about other models but there is a way to turn it off completely for SLK's (gotta love the net! *L*) MB doesn't advertise it but here it is:

Turn the ignition key to the first accessory position, making sure the dash display shows the odometer. The SRS airbag light should be on. Press the trip odometer reset button three times rapidly before it goes off. If you do this right, a screen will appear showing a voltmeter. Then press the "up" arrow on the left side of the wheel twice to take you to the "ESP dynamometer test" screen. Using the plus (+) button on the right side of the wheel, select "on." And then start the car. Warnings will appear informing you that the ESP, ABS, and BAS (brake assist) aids are now turned off and you're on your own.

It's not as complicated as it sounds *L*. To launch the car (still on the stock Pirelli's), I put it in "sport" mode, ESP off, and go half throttle to get the car moving, then quickly foot to floor as traction allows. The Pirelli's aren't the best tire I've ever had for traction so I find the best launch is with ESP "off", instead of completely disabled as I described above.

 

Sorry, didn't see your question earlier! Anyhoo, the C class is currently between full re-designs with the 2008 model year seeing the new version. As Bob pointed out, the latest AMG C up to this point is the C55 with the same 5.4L NA engine as the SLK55. The 2008 AMG C class will have the new 6.3L AMG engine with output pegged at 450hp for that model. Basically the same engine as the current AMG's CLS63 and E63, slightly detuned (on paper anyway) to keep from stealing all the thunder from it's bigger brothers. The new C63, at several hundred pounds less than those larger models, is going to be one quick little car for sure.