Gimp is a fine choice but requires serious time and effort to learn to use. Probably not a good choice for someone new to PP, or has limited time, or who generally isn't comfortable with a steep learning curve.
Some like to start with a mass market freebie like Picasa. Just to get used to the idea of PP and learn some of the terms and actions in a generic way. Training wheels, if you will.
Others jump to Photoshop Elements, my choice for neophytes. It's generally available at an attractive price these days: $50-$75 USD. Elements offers two levels of guidance and also allows you to take the training wheels off when you're ready - three approaches as you become more capable and competent.
If and when you need to move up, noting that many don't have that need, Gimp and the full Photoshop are well worth investigating. But that is another question entirely.
Last edited by glanglois; 12-03-2010 at 06:00 AM.