Guapo,
Here's my 2 cents worth. Since the mtb is working fine as is, I would focus on getting the road bike built up. Then you will have two working bikes. Once you recover from the road bike project, save up your nickels to work on the mtb.

Twice in the last couple of weeks I have gone to air to top off my tires when I was ready to head out to work or on a ride only to discover flats when I really didn't have time to change them. In both cases, I was VERY glad I had a second bike to throw my gear on and head out with minimal lost time.
Regards,
Raymond