There's a lot of differing philosophies on driver selection for those starting out, but I do recommend learning to throw your putters and midranges well. Those will teach you the most about reducing torque on the disc, as well as generating spin (or snap), which is how big distance is archived. A 170ish Roc or Buzz would be a good disc, as well as a 170+ putter (wizard, aviar, challenger, rhyno, magnet...whatever feels good in your hand) would be great starting discs.
While you could go with a distance driver like a valkyrie or a beast or wraith, you may want to start out with a fairway driver like a Gazelle, Cyclone, or Sabre (which are pretty much the same disc from the 3 major manufacturers). These particular drivers are quite versatile, allowing you to learn to work a variety of angles (both hyzer and anhyzer) and lines (both high and low) without the need to buy too many discs. The thing with the high speed drivers is that you need a good amount of arm speed and snap with minimal torque to get the desired lines, which is a tough trifecta to put together when you're starting. Also, the slower fairway drivers are less nose sensitive, so you're less prone to have throws go all over the place. Personally, when it comes to weight, I tend to recommend something in the 168 range for starting out, because it teach you to snap the disc without torquing it over, as a lot of beginners do because they're throwing discs that are too heavy for their technique.
It might be worth your time to check out http://www.discgolfreview.com
, read though the articles, and read through the information on their forums. While there's a lot (and I mean a lot) of crap to wade though there, I have found some amazingly insightful information into good technique.