Surprisingly enough, there aren't that many programs out there that focus on your baby's interaction with your computer. Baby Shield has a pretty crude interface made up of big action buttons and a floating image, but we can let that go as its obviously intended to attract the attention of your toddler.
We found the idea behind Baby Shield quite original, as every time your baby presses a button on the keyboard the program will show an image associated with the letter. The song that plays in the background will surely sound annoying to you but could just get your baby into a good mood.
If you really want to protect your PC from your baby's curiosity, you can always lock your screen. Or you can install Baby Shield and let your toddler play around with your keyboard. It's not sure it'll grab its attention though.