Thanks for the advice guys. I took the car to Interstate and they checked it out. I also called a Mercedes Dealership. Well apparently the stock battery calls for 660 cranking amps. Interstate stocked the equivalent of that, but I went up one step to the 850cold/1085 cranking amp baby. This should keep me happy.
The problem was one my battery was very old, two it was only a 450 cranking amp battery that some monkey had put in. Now I know I will be OK.
One puzzling thing though is that Sears said I needed a special battery with some kind of breather tube on it. Since we all know that Sears is crap I then went to Interstate. They said this was only done in the old days on batteries left under the seat or the trunk, not sure I follow this, I assume he was talking about a battery in transit, hmm. I assume this breather tube is not necessary and my new battery works fine without it. (even the Mercedes dealer said their battery had no tube on it and this was an outdated function). If anyone knows please enlighten me out of curiosity.
Thanx for all the feedback guys