This is my first year playing. I played a lot of baseball as a kid, so the mechanics came fairly naturally for me.
I had started off with a cheap, Wal-Mart driver (Wilson, 10.5, "men's flex"). Naturally, I had a pretty consistent, nasty slice. I had viewed paying $200+ for a driver with a very skeptical eye. When I saw this driver advertized for $150, I decided to give it a try.
Boy, am I glad I did. This may sound cliche, but this purchase has made all of the difference in the world. Before, I would slice essentially every tee shot. Now, I might have 2 or 3 a round. I'm actually finding the left side of the fairways now, and with the straighter trajectory, I'm getting an extra 20yds of distance.
BTW, I went with the 9.5, S-flex. It turns out my skepticism was misfounded.