Do it! You will not regret this decision!
I thought I'd need a "supercomputer" for all the 3D anatomy software they told us about at interview, but it turns out that you can't get it for personal use unless you want to spend a couple grand. (we have it on computers in each of the private study rooms instead.
So I bought a 15" MacBook Pro (mid 2011). It's got the quad core i7, 16gb RAM, 750GB hard drive, 1GB video card etc. All it does is hurt my back now, I could have gotten by just fine with a little netbook for like $400.00 (but I wouldn't since I'm a Mac user).
Anyway, those air's are fast, and light. That would have been the ultimate purchase now that I can look back on it.
Oh, and anytime anyone wants to swap gore stories, I'm down. I've seen a lot of good stuff over the years.