Seconded. There's more than a bit of literature documenting the benefits of mindfulness/insight/vipassana meditation, which, besides an increase in the ability to focus, include reduced stress and anxiety:

http://bit.ly/9OKHt9 (google scholar search)

And "...a nuts-and-bolts, step-by-step guide to Insight [Vipassana] meditation...":

http://www.kusala.org/udharma4/mpe.html

I second the recommendation for Mindfulness in Plain Language. Great book.