starter bike

I'm looking for a starter bicycle, but I have a whole bunch of specifications... and I would really appreciate some help with what to buy.

First off- I've cross-country cycled before (in India), but its been about 7 years since I used to do that, and I've rarely been on a bike since then.
Secondly- I'm living in Atlanta, GA in the US right now, and this place is hella hilly. Lots of ups and downs.
Thirdly- I plan on using the bicycle for the occasional commute, but mostly for recreation/fitness in the area and I plan on hitting the local bike trails as much as possible.
and Fourth- I'm kinda on a budget.

Anyone with any sage words of advice?

what's your budget?