I use Paint.NET's magic wand tool, and just change the tolerance level on it. If it comes out choppy, you just need to up the tolerance level.
Did you honestly not know that, or are you just trying to make me feel pro?
"Sex is like a velociraptor: Despite your movie-fueled lifelong neurotic obsession, it is unlikely to be found in your house." ~XKCD
Well, my school has the CS4 suite on one of their computers as well, but I don't know much about it as I find it too hard to use. :P
Try downloading Paint.NET. It is waaaaayyy simpler.
"Sex is like a velociraptor: Despite your movie-fueled lifelong neurotic obsession, it is unlikely to be found in your house." ~XKCD