Is there any software available that would let me take photos of my sons and give the picture an oil painting effect?
There are lots of ways to make your photo look like a painting, some of which you may already have in your toolkit. The simplest method is to use an effect filter that, with a little bit of input from you, creates a painting automatically. Then, if you really want to dive in, try a dedicated program.
Both Adobe Photoshop and (since 4.0) all versions of Photoshop Elements ($650 and $90 direct, respectively; www.adobe.com) have fun and quick painterly filters. To try them, open your image and go to Filter > Artistic > Paint Daubs.
You can control the brush size, type, and sharpness. Just don't make the brush size too big, or you won't be able to recognize your children.
If the automated methods leave you wanting more, try the dedicated painting program, Corel Painter Essentials 3 ($79 for box version, direct, www.corel.com), which we used in our example. Unlike its big brother, the $429 (box, direct) Painter IX.5, it's got a simple interface that's easy to learn.
You can even use your photo as if it were your palette, choosing from a nearly infinite supply of brush, paper, and paint types. Apply your brush to it, and watch as the picture turns into paint.
When you're all done, print your masterpiece on canvas. Adorama makes real coated canvas, Projet Fine Art Canvas, that you can frame to fool your friends ($16 for a 10-pack of 8x10s, www.adorama.com).