If you're combining images into one at any point, then there's probably a better way to do it. If you design from the beginning with CSS sprites in mind, you should always be working from your spritemap image. Then it's a matter of time spent positioning vs. time spent managing the images themselves in your document, which I've found to be pretty even.

I really didn't touch on this as much as I would like in the post. Would a process post on this be of interest to you?