Before you get those 1.25 inch tires, you might want to check the chart below that I stole from Sheldon Brown's website.



I believe that 1.25 inches is between a 32 and a 35 so you'll want to make sure that the interior width of your rim is 21mm or less. If the outside is an inch, you're probably good.

The other thing to consider is ride quality. You're going to feel the bumps more with 1.25" tire, especially on a 26" rim. You're going to have to be much more careful about keeping the air pressure up and you may have more issues with flats.

And in the end, the bike is still a hybrid/comfort bike. The performance gains you get by going with a narrower tire may not be what you hoped for.