I currently ride my mountain bike on bike paths and light trails. However I would like to also be able to ride my neighborhood streets and other quiet roads. I have a Gary Fisher Mamba WSD 29er. Its great for what Ive been using it for but when I try to road ride I feel worn out afterward. Like that maybe that bike wasnt meant for asphalt?! Anyway, would getting a road bike be in order and also what would be a good entry level one for a gal thats just over 200 right now? Hoping to find a craigslist gem for this one since I bought my GF Mamba brand new just this past may!

Thanks ahead of time!