Road Brifters with MTB Derailleurs I've just bought a lovely Surly touring frame and I simply stuck all of my mountain bike components on it. 

That means I've retained a flat handlebar. I'd really like to stick drop bars on though and change to road "brifters" without changing the drive train. 

I've tried Googling this and it seems to be complex issue so any advice would be most welcome. I have Shimano Alivio gears, front and rear plus a Shimano Diore crank (with the external bottom bracket type). The rear is a 9-speed cassette (11-30) while the Diore triple crank is a 48-36-26. 

I really want to stick with this, not just because of the expense of buying a whole new drive train but also this set up gives me a really low bottom gear (30 on rear 26 on front) for getting up hills with a fully laden touring bike. 

I understand I may need a new front derailleur but I may be able to get away with keeping the rear derailleur and using a ten-speed brifter such as a Tiagra with the 9-speed cassette. Is this right? Any suggestions would be greatly appreciated.
I don't see any problem with doing this on your bike if you use Shimano drifters. Generically there are two areas you'll need to consider:


The actuation ratio of the shifters, and
The brake pull.


Shimano 9-speed road and mountain derailers use the same actuation ratio. You should be OK here.

You don't mention which Surly touring frame you have so I can't be specific, but if its a Long Haul Trucker or Disc Trucker, your odds are good that the brakes will be compatible as well. With cantilevers you'll be OK as road and mountain versions use the same pull. V brakes will be a problem, they are not common on road bikes and the pull is different. I don't think know of a set of brifters for V-brakes. Similarly with discs, make sure that you are have, or are willing to switch, to road discs.