As a first time commuter you might find you actually like riding that bike to and from work, as it gives you a more stable platform to ride on, even in traffic, and you won't have to worry as much about having to avoid potholes/sand/etc.

What I would say is take a weekend day and ride the trip, get used to it on a bike, etc, and work your way into riding with cars. Another option is to do the switcheroo...drive to work, bike back, bike to work, drive back, until you're more comfortable.

I know how frustrating traffic can be...but you'll gain confidence if you try the trip before you 'have' to be at work.