Two year olds can definitely learn to use and respect the computer. I have taught each child and later, my grandkids to use them. Thirteen years ago, my three year old could bring up her games in DOS, now she is designing the school sweatshirts in photoshop. My son has his own computer repair shop.
I usually start with the keyboard. The concept of one finger/key at a time is tough, but they get that pretty fast. Just putting up a word processor with big colorful lettering is a good start. There used to be an old DOS game called Dannys First Program, which was perfect for little ones. Each key launched some colorful, noisy event. I wish I could find a modern equivalent.
Once they get the idea of respecting the keyboard, they can practice the mouse. I put an 'X' with a Sharpie on the left click button. There are lots of simple (flash type) matching games online and this is a great way for little ones to learn to point and click. My three year old grandson is already a master at pbskids, noggin and cartoon network, all have lots of fun and educational games for kids.
Little ones see us use the computers all the time, and they are so curious. You might as well teach them early to respect the computer and how to use it. Those skills can help them for the rest of their lives.