Question- you stated that you have a comfort/hybrid- does that have a suspension fork and is there any way to lock it out? You might see if your LBS could swap on a rigid one for you.

Another option, though I go back and forth on this route myself, is buy something for cheap off of BD. If you can live without brifters, a road bike can be had for $299. You could use this as a fast and fun commuter and your current one as a rain bike/back up beater (after you put a longer seat post on and address any other fit issues).