Originally Posted by orcus332
This is where I am confused. Does the final volume of starter even really matter, or is it more about the amount of DME that you use that will influence how many yeast you end up with?
If you're not lost yet, congrats, i owe you a beer.
Well, neither, really. What's important is the cell count that you pitch.
The idea behind a starter is to take a particular amount of cells (say 100Billion, which is what you get in a single vial) and propagate the yeast until you get the right amount for your particular wort. On the way you are also proving cell viability, and improving cell condition so that the yeast can get right to work on your wort.
The amount of cell growth is nonlinear, and is a function of inoculation rate (how much yeast did you put in the starter) and starter size. Mr. Malty figures out the inoculation rate based on what kind of yeast you are pitching (vial, slurry, etc) and how old it is. Using that, and the numbers for your wort, it solves for the starter size you'd need.
In your particular case, since you are propagating yeast from a bottle, you are going to start with very little yeast, and it will be in very poor health (compared to if you had a full vial of healthy yeast). Therefore, you should treat it carefully and let it gather strength slowly. This means that you should definitely use a step up starter, and further more, that you should step up not only the volume but also the gravity.
I would suggest starting with a 50-100ml 1.025 starter, stepped up to 250-350, 1.035 and finally 1.5L 1.040 as Mr Malty suggests. This way your yeast gets a chance to work on wort that has lower osmotic pressure first, and propagate healthy cells first, before it is called upon to work on the "real" starter.