You might not use the computer for your preschooler. We do, but just a little. Actually, it seems like in the past two months, or so, we have been using the computer 1-2 times a week instead of 1-2 times a month like before.
There are two sites that I really like for M, my four year old.
Starfall-We especially like the Gingerbread Man and Pumpkin games. (See above for M's demonstration.) M actually will do them completely by herself now. She will even read her younger brother what the questions are (memorized) and the choices-even if she doesn't let him have the option of choosing the answer.
Duck's Alphabet- This game is from Word World, a show on PBS that is rather clever, in my opinion. A child can systematically go through an alphabet adventure in this game over time. My daughter quickly caught on to how to do this game herself.
Once in a while we'll do a Fisher-Price game. (This site is also appropriate for E, age 2.) I only visited Nick Jr once, but I printed off some neat phonics word family printables (-ug, -an, -at) when I did. (And, yes, you can find non-character stuff if you look very carefully.)
Where does your little one go if and when they use the computer?
(Meghan also has her own "computer" that connects into our computer to be used. She doesn't use it often, but does like it. She would love to be allowed to use the computer daily...but we don't allow that. I'm fairly
obsessed attached to our laptop, but still want limits on children's use.)