Dab, I only use natural light and my typical subjects are running, playing, jumping toddlers, so adding a sidelight isn't really an option at this point, sad to say, but I appreciate the tip! Gonna tuck that away for later.
Viking, I don't have a speedlight, but I do believe that I have an AF assist lamp somewhere in my custom settings. Gonna try that. Thanks!
If you want to see an example of what I'm talking about, there's a shot in my flickr:
She was fascinated by all of the dewdrops on the flowers. on Flickr - Photo Sharing!
The focus is tack sharp on the highlights, but at 100%, her face (though not out of focus) is a little soft. I love backlight, so I this is annoying me to no end.