Digital Greeting Cards

About once a year at this time we snap a few pictures of our children and put them in a greeting card generator walmart.com. It shows a scene, a few photos and a text saying "Merry Christmas".

The choice of these cards are generally poor, and I would really like the design of my own (the easy way, using existing images, etc.)

What software is there that will allow me to do. Preferably, I would like something freely available, such as The Gimp

Thank you!

I make mine in Photoshop. Any program that allows you to image to a blank template should work. Just the size of the model to the size of your basket and start designing. The carts, you can find in any store of office supplies at home.