I agree that the drum software is the way to go. Plugging one mic straight into your computer will not sound good at all. You can get some interesting sounds that way, but nothing that would be conducive to actually getting a "decent" drum sound.

If you want to record a drummer; you will need an interface with 4 or more inputs and the proper mics. There are many, many ways to achieve this but you will spend much more then what it would cost to get EZ drummer. It's all laid out for you and sounds good already.