I have been using LeapFrog's Kindergarten Skills and Beginning Reading Skills with my four year old. She has been doing real well with them and even sounded out a word (c-a-t) and knew what it said on her own today. I was very proud of her!
I'd recommend giving these books a try, even if you don't plan to homeschool but you still have preschoolers at home with you. I use them during nap time so she and I can sit down and work on the books together.
I'll post the links here so they can be easier to find through Amazon. I tried to find them through Toys r Us website, which is where I got them, but couldn't find them there.
Anyways, here they are:
Hope you find them useful!