right now nashbar.com has their flat bar roadbike on sale for $399 and free shipping. it would probably be about 7-8 lbs lighter than your mtb and it has a carbon fork. it's essentially an entry level road bike with flat bars instead of drops. you could easily upgrade it to drops if you so desired as it comes with a 9spd drive train. most entry level flat bar road bikes come with 7 or 8 speed drive trains so upgrading them typically is more of a chore. the free shipping is only for today and tomorrow but you should really take a serious look at this. you can pay your LBS to assemble and still be under $500 and have a nicer bike than the 1.1 in my opinion.
http://www.nashbar.com/bikes/Product...0_10000_202339