If I may chime in here, we make (at least for now) a nice 700x23 tire with a kevlar puncture protection belt. It's called the Blizzard, which I've always thought was an odd name considering that it's not a winter tire in any way. The wire bead version retails for $29, and the folding bead version retails for $36.95.

http://www.schwalbetires.com/node/1391

Also available in a 700x25.

For those suggesting wider tires, I agree in principle, but the bike that the OP has will not likely work with anything wider than a 25mm tire. As the name implies (Cannondale Criterium), it was a purpose built bike for racing and the tolerance between the chainstays is fairly narrow.