I just got home from Big O tires, I Caved in and just went with some 225/50/16 Pirelli p Zero Nero's. the sales man insured me that they were identical to the s-02's on dimention and size? He also told me that they are the best tire in the world... Is this true?

 

There are two versions of Pzero Nero's: one is summer and the other is all-season, the all-season has M&S stamped on sidewall. The M&S version is one of the best all-season tires, the summer version is okay, but not the best summer tire.

 

Well now that you've "done the deed", no point in regretting it. But for your own reference, take a tape measure and measure the "footprint" of the old SO2 then go measure the footprint on the new tires. You will find that the new tires will have as much as 3/4" to 1" less rubber touching the groung.
Your car will be fine. It'll serve your well with those tires but you may have to get used to its new handling limits.