Thanks for the great replies so far. The part about being bent over to put more power to the pedals makes tons of sense, disappointed that I didn't realize that aerodynamics wasn't the only benefit to being tucked. Come to think of it, in my current upright seating position, I do feel myself pushing the pedals away from my body to the front, rather than really using my legs to drive the pedals down/around if I were more directly above them. I'll definitely be dropping my handlebars a little bit when I get home. (They're currently at a grandmotherly upright position.)

I'm also relieved to hear that the high-tech lightweight components don't make too much of a difference. That was the upgrade I was the most reluctant to make.

As per the tires, I'll begin to make sure I have adequate pressure in them. I've only been commuting for 2 weeks, so I'm very ne to cycling in general. They're "road slicks" so I won't go crazy trying to get narrower tires. The thought of riding in Manhattan on the super-skinnies kind of makes me nervous as it is.

Thanks again for such good information. I was thinking that the technology had a lot to do with it, but it seems that the most important things is that I really should just get into better shape. I figure I knew this coming in, but just didn't want to admit it to myself. No shortcuts in this world, hahah.