Well, at least you gotta change it to a better tire first. I got a pretty nice 700x25 road tire. However I got flat all the time by the glasses on the street. I've experienced 3 flat tires on a 56miles trip. Recently I bought a new pair of tubes and those situations have gone.

It's called "Forté Road Thorn Resistant" and costs about $6.00usd.
http://www.performancebike.com/bikes...1586500_400233

The tube has 1.6mm thickness rubber. Compare to Michelin 700x23c tube (0.7mm), it's about 2.25x thicker. But it weighs 260grams about 3 times heavier. But you cant feel the difference =].