Calories in Italian dressing pasta salad?

I had pasta salad at school today with italian dressing. Our caf sells pr-packaged meals like that, so I estimated that it was about 2 cups worth of pasta. I was just wondering how many calories would have been in that? I know regular pasta salad with mayo is really fattening, so I was concerned after I ate this. I was thinking maybe 400-500? Would that be about right? It was whole wheat penne pasta with chopped peppers.