I know Steven Erikson (Malazan Book of the Fallen) has a degree in anthropology and archaeologist.  He developed his series from a roleplaying world with Ian Cameron Esslemont, who is also an archaeologist but is getting a Ph.D in Lit.

I think all you really need is training period, it doesn't really matter ultimately if you're driven enough.  I'm sure it's a better asset than others, but many degree paths focus on writing at some point, even the sciences.

I have a bachelors in physics and you have to be able to write technical papers.  While the subject matter is different, you can use that knowledge in other ways to help your writing.   

I personally decided I wanted a physics degree because I wanted to write a science fiction or science fantasy book with magic that follows natural laws and not have space fighters making instantaneous turns without accounting for conservation of momentum and moment of inertia or a wizard being able to use as much power as they want and it not really effecting them personally (why I like that Jim has Harry do stuff like when he's sucking the energy from Lake Michigan, uses fire at an enemy and the lake freezes, which is consistent with the real world) and what I'd classify easiest as Harry Porter magic. 

Unfortunately, I haven't made much headway on my project (other needs get in the way and still a bit uncertain where I want to go with it) but it's something that's always churning in my mind these days.  In the mean time I just research some interesting things that I think I want to use (thanks io9!). 

I've thought about taking some creative writing classes but it's not something I've felt was absolutely necessary for me.  Just means I'll have to be more self-taught about it.

My friends and I had a great time at the signing last night.  The Q and A session was hilarious and it's a shame it was only an hour long.  I could have listened to that for hours.  It was definitely worth the drive from Grand Rapids, MI, even with the requisite hour and a half delay because of Chicago drivers and rain.  I started the Dresden series only a month ago but I've become a big fan and the series is quickly becoming a top favorite of mine.  Meeting Jim just made that even better.  Keep on writing.