In reply to Tim Chappell:
Classes are best by far, but be prepared to search a bit for a teacher or style you like - most good teachers will give the first class free or for a reduced fee, no obligations. That said, you'll need to give it a few goes before deciding if yoga is for you or not. Theres a knack to the mindset as much as (more than!) the postures. Dont write it off first go, easy done with a duff teacher or a style that doesnt suit.
Re: DVDs - A humungous number of teachers have a you tube channel or clips these days. Worth a look before committing to a DVD (if only to check their accent/style of teaching doesnt grate!)