Have you ever found playing against your computer boring? Computer are not great at simulating particular playing strengths and of course, they are way too strong to play against at their optimum level.
But, there is a great way to have an interesting game with the computer: simply do a “position setup”, remove say, a rook from the computer’s pieces, and try to convert the advantage against the computer. If you master a rook-up starting position, try playing with knight-odds, pawn-odds, etc.
It is easy to do position setup in Fritz and presumably other software like Chess Assistant, Scid, etc. If you don’t have any of this software, I recommend using the simple and easy-to-use program Tarrasch, which comes with a pre-installed Rybka 2.2n2 engine. Or go to the Tarrasch homepage. I discuss the Rybka engine more in my article World’s Strongest Chess Program for Free.