i, too, started on rock band, lol.
it got me the ability to play a basic hi hat beat, but fills and other stuff you will need to learn from scratch.
the layout is much different feeling for toms and cymbals.
you can get a good head start at freedrumlessonsonline as they have great beginner tutorials.
also, they will help you in setting up your set properly - ie snare position and height, tuning.
if you buy a set, dont get one with free cymbals as they are all crap.
you are going to want to get decent heads, too, as the ones that come with most sets under a grand aren't worth spit.
plan on 300 for a minimal 5 piece shell kit, 200 for cymbals and $75 for new heads . I would suggest going 400 to 500 for a better shell kit like pearl, tho, as you will prolly regret it later - or keep it for gigs as i did when you upgrade.
if you want double bass, plan on $200 for a decent pedal.
it is a great hobby , but is also quite expensive and addictive!