Until you get an answer from somebody who knows their stuff about yeast; let me shoot from the hip here. If you don't mind, I will cover some important factors that you did not include.
Temperature is critical. Make sure the starter is the same temperature as the wort when they mix. Don't shock the yeast while trying to equalize this before you pitch. Do it gradually. Match the temp that the yeast company says. Oxygen is also important. Make sure the wort is aerated good.
The starter, as is, will add some volume to your fermenter. I generally don't sweat that. Some folks put the starter in the fridge or let it sit so the yeast falls and flocculates to the bottom. Then decant the wort off, leaving most of the starter behind. Then slowly adjust the temperature to fermentation temp and pitch. I intend to do this in the future but have been rushing the process with fine results.
A basic starter is better than nothing, but you want to consider the gravity of your wort when deciding the size of your starter. Other factors that affect the actual yeast count are the volume of your starter, the temperature it sat at, and weather or not you let it sit, or if it was occasionally shaken or put on a stir plate.
To cut through my rambling, visit Mr. Malty and use the "Rate Pitch Calculator". http://www.mrmalty.com/calc/calc.html
Your beer is gonna be good. Read "Yeast", by White & Zainasheff to know everything you need.