First, it's only a couple of days, so you might as well wait to see if they introduce something amazing at the expo.
Second, whether it's good enough depends entirely on what you plan on doing with it. Basic boring things (internet, email, word processing) are fine, but it's not going to be a great games machine or good for intense video editing (iMovie won't be too bad, though.)
edit: If you're switching, give yourself at least a week of just using OS X to get used to it. Don't put Windows on it straight away, or you'll never get properly into OS X.