For those who would like to experiment with image-editing software, but don't want to pay a fortune for Adobe products:
Introduction to GIMP; Download:
GIMP 2.6.10
GIMP is
free, and designed to run under Linux, but can be installed on Windows machines with the proper binary installer (follow link on download page). It's easily comparable to PhotoShop, and has great support from the user community. Many people have tutorials and examples online.
I use GIMP for all my photo editing needs; I particularly like the easy manipulation of contrast, curves, and color balance. Great for assembling more creative images, too.