You definitely need to look into gear ratios and play around with which ratio feels like something you can work with for an entire commute. Go read about gear ratios if you are a newbie to that concept.

As far as fitment goes, you should look into a comfortable relaxed fit. There are many ways to fit yourself on a bike. If you go for a more aggressive fitment you will fatigue more easily.

I highly recommend an IRO Mark V frameset if you can find one. Jenson bikes sells them for $270. If you can find one, I'd say this is your best bet as a very versatile frame. It can support front and rear brakes and even a water bottle boss. The tubing is teardrop shaped so it is stiff, and the geometry is quite relaxed. You'll feel very comfortable with this frame. With $330 left, I think you can work out the rest of the components, including a $100 white DV wheelset. Just be weary of your fitment on the bike when building up, and gear ratio - super important.

If you can throw down for it, I also think the bianchi san jose is a great complete bike :

http://www.bianchiusa.com/archives/1...gear/san-jose/

With a 42/17 ratio, it will give you that ride you're looking for and won't fatigue you. The components on this bike kick ass and as a complete piece, it rides amazing with the knobby tires. It also looks very classy (much more so than white DV's, in my opinion).