Custom vs Stock for first bike?

[KnottedYet]

One caveat: the geometry of a bike isn't just about fitting the rider's body, it's also about fitting the rider's positioning preferences.

I could position one person's body 80 gazillion different "correct" ways, and some of those ways will work best with very different frame geometries than others.

If you have "zero experience riding", you may want to buy a bomb-proof $400 bike (like a Kona Dew, which can later become your utility bike) and ride-ride-ride.

As you gain experience riding, you will learn your preferences. Once you really have solid preferences, then you can get a custom bike that fits both your body and the way you like to ride.

(Here's the Kona Dew http://www.konaworld.com/bike.cfm?content=dew The smallest size is 45, which is also the smallest size in Kona's dedicated women's line "Lisa" variants.)
(And, if you are looking for a commuter like you say, you really don't want to risk having a lovely custom bike stolen or vandalized while you are at work. Do like the "pros" and use a cheaper bike for commuting.)