Suggestions needed.

My commute
17 miles each way
Mostly flat cement trails (pretty smooth ones)
about 3 (total) miles of hills at start and end of commute
I occasionally add 10-15 miles to the return commute for 27-32 miles on the return trip
Fastest morning ride was 16.4mph average with mild head wind
Fastest evening ride (when I don't care if I sweat) was 17.1mph average also with a mild head wind

Current Bike
1998 Specialized Hardrock Sport FS
Computer
Shimano SPD pedals and shoes
Slick tires
Clothes and water carried in a camelback
Bar ends so I have more than one hand position
C-cell style hallogen light used when I ride early (just a cheap one) - only good for being seen
Blinky red light on camel back
Solid red light on seat post

I'm hoping to pick up a second bike this winter to use next spring/summer/fall for commuting and training. My intention is to also use it for some long tour rides next summer along with weekend rides that tend to be 30-50 miles. The MTB will be reserved for winter duty or nasty weather (fenders are on the buy list for the MTB).

I could use suggestions for a good sub $1000 commutor w/ drop bars, disc brakes, decent rim set, long enough wheel base for panniers, comfortable enough to commute and do longer 50-100 mile rides with.

Keep in mind that I'll be using the MTB for bad weather commutes and converting it to studded tires in the winter.