Well, as I see it based on my experiences with computers, a computer won't play brilliantly at 1300, but it won't make really bad errors either. A computer playing at 1300 level is simply not going to give away a piece with an open blunder. The humans you are playing at that level, and lower, will do that occasionally. So, as soon as you make a bad error against a computer, you're cooked. Those dang computers play like machines!
Some computers can be set to play either deterministically (always the same best move, in its opinion, in the same position) or non-deterministically (randomly choosing between multiple good moves). The latter is more human like, and it also prevents you from memorizing the computer's opening lines.
I've played chess on and off for most of my life, friendly matches here and there, and the occasional 10games in a row against the same person. About 3 months ago a friend of mine got chessmaster so i've been going through the program and started off with ranked play. I usually play 5/10min blitz games, and in the beginning i was keeping up with game profiles in the 1300's. Then i started doing all the tutorials the program has to offer, and since then, my ranking has steadily decreased (vs the programs). I've continued to play online chess and my chess play seems to have increased online against other players, but i just can't seem to beat the computer.
Do the engines somehow record the way you've played in previous games and get you to try and change your playing style by playing certain openings? Or do they keep to an exact pattern and once you figure out that pattern you move up to the next level..