Where is the radiator drain plug for a 2000 Chevy Cavalier?

It will be located on the bottom of the raditor or at some other low point on the cooling system.

To be more specific, on my 2003 Cavalier it is located near the very bottom driver's side of the radiator, and is on the front of the radiator, not behind it. The plug is just a small white plastic button about the size of a nickel as I recall. The plug is hidden by the front air dam, and you can just see the plug if you look at an angle to the right through the right side air dam vent. You have to reach up and in to get at the plug. Its not a straight shot from the outside. A small hexagon Allen wrench is needed to open the plug, but a large short screwdriver can be used to close the plug. Its plastic, so don't use a lot of force. Go slowly, take it easy.

The plug does not come off the radiator. You just turn it enough for it to pop out a little, and the radiator fluid flows out. The vacume in the radiator system is very strong, so I had to remove the radiator reservoir fill cap up above in order for the fulid to flow out.

When I drained the fluid, only about 3 quarts out of a total 8 quarts actually came out, so its not a total change by any means. I hate to use a garden hose to flush the system, since my tap water has high mineral content. I'll just drain 3 quarts every year, and feel that the fluid is pretty near to being new and clean. I use the pink fluid and distilled water, so it should be clean.