I need an image program in the near term that's either free or comes with a free trial, then I'll weigh whether it's worth keeping, which will do the same as Photoshop's Magic Wand tool. Of course, I believe there's a Photoshop trial or maybe the Magic Wand is also in Illustrator, but I really just need this one tool for a week or two to do something specific.

Any suggestions?

ETA: Win7 is the OS