Get a bathroom scale, a block of wood about the same height as the scale, and get on the bike while next to something to steady yourself. Put the scale under the front tire first, and then the back tire, and see how much weight is on each tire. Then use that Tire Drop article to see what pressure would be ideal for you. I run 85/110 in my 700x25C tires, and I'm 190 lbs. My MTB with 1.5" street tires and rigid steel fork gets 40/60.

Not sure if you want to drop a little over $100 on that bike, but if you did you could probably switch out the fork to a carbon fork from Nashbar. I LOVE LOVE LOVE the way my road bike feels with carbon fork, and IMHO it rides better than my MTB with the rigid steel fork and larger tires.