Summer Challenge is a truly classic, keyboard trashing, sports game. :) It has all the necessary ingredients: it looks good, it's fast, fun, diverse and challenging. It will cause pain in your arms and muscle spasms, but none of that can compare to the joy of braking your own record in a discipline :)
However, be careful not to play this game in front of many people. The sight of your arm hysterically twitching in an attempt to press as fast as you can is not the most peasurable one. Now, about the game itself...
It offers eight disciplines: kayak, hurdles, pole vault, high jump, javelin, cycling, archery and equestrian. It will take a lot of time to master those disciplines. You can also choose your opponent player's skill, ranging from amateur to world class (practically unbeatable).
Controls are very simple. In most cases you will only use and space bar. In some disciplines you will have to steer by using the arrow keys but that is pretty much it.
You can create custom tournaments and compete against your friend so, in a sense, multiplayer is supported.
Graphics and sound are great, however sound will not work under WinXP. You may perhaps have trouble with starting the game. There are 3 or 4 executables with a similar name. I recommend using sum.bat for starting the game. If it doesn't work the first time, try a few more times and it will eventually start.
Also, in case the game exits when you try to train or compete in a tournament, you can fix this by going to the options screen and then returning to the main menu before trying to start playing. That is pretty much it! Enough talk, go win your first Olympic medal! :)