Ok, here's the deal.

I've got an old mountain bike that i'm converting into a commuter.

One of the things I want to do is put a set of new drop bars on it. I'm assuming the original stem has a 25.4mm clamp, and i've noticed that the smallest diameter that "new" drop bars come in is 26mm...

Are there any stems out there that'll fit my mountain bike headset and accomdate a 26mm bar?

or should i look into replacing the fork altogether with a threadless one (i think that's the name? the ones that extend all the way up through the top of the frame, and you attach a stem right onto it?) and a new stem? I'm assuming that'll cost me a lot of money and won't be worth it...