I converted to a MacBook Pro in 2008. Yes, it was more money, but @ 6 years old, it runs like the day it was new, even with the very latest OSX Mavericks installed. Find a cheap 6 year old PC that will run the latest version of Windows!
There is certainly a learning curve. If you are a POWER USER of MS OFFICE, the Apple counterparts (Pages, Numbers, Keynote) are not as well designed and operate very differently, which will require a larger learning curve. Beyond that though, the learning curve is nothing to worry about.
Here in my office, we dole out lower end laptops which rarely make it 3 years before needing replacement. All the while, my 6 year old MacBook shows no signs of aging. Cost vs value is the measurement that matters. Not just initial purchase price.