Here's a microphone preamp that I've used with great success. It's great for microphones such as the Panasonic WM60, and perfect for use with sound cards or the preamp inputs of your stereo system.

The amp is inexpensive and easy to build, and it performs well with a couple of AA batteries for power. The microphone will get power from this circuit, so be sure and observe proper polarity. The Panasonic microphone is pretty sensitive so it will pickup everything in the room. Be careful not to overdrive your inputs; Just turn down the gain.