It's hard to recommend programs unless we know what type of computer to recommend them for. Are you using an Ipad or another tablet? Are you looking for something online?
Starfall is available online and as an Apple App for Ipads, Iphones, etc. My daughter became somewhat obsessed with that when she was around 33 months, but my son hasn't taken to it the same way. My daughter also used Bob Books sets 1,3,4, and 5 which she recently completed. After set 5, children are prepared to read chapter books.
For math, I think working with manipulatives is better than working on the computer. The Montessori bead stair, or a set of unifix cubes can be used to model simple equations. Having said that, there are Montessori based computer games, too.
