I tried out the Specialized Langster and Jamis Beatnik this weekend and i thought both were pretty tight, but my friend who is a very serious biker discouraged me from getting the Jamis. I need a good bike for commuting in NYC and I want to be able to upgrade on it and keep the bike for awhile. Can you recommend a bike (or two) that falls in the same price range ($500-$700)?

thanks!