I have the same Serfas Drifter FPS tires in 26x1.5 that were mentioned above. Great tires and not a single flat yet in 350 miles so far *knock on wood*

I think the things I'm most dissatisfied about my bike right now are the small rims/tires, and the gearing. That's why I'm hoping to get something more modern/road oriented in the not too distance future. Plus the look. My rigid front forks are length-corrected to replace suspension forks, and they're very wide to accommodate huge tires. I prefer the "tight" look of road bikes with very little space between the down tube and front tire, fork just barely larger than the tire itself, etc. But that's just my personal tastes.