On the page in sound you seem to be looking at, if you highlight the microphone and click properties, there should be a box on the bottom that says "enabled" and it should show which plug the microphone needs to go in. Windows 7 will normally recognize when the mic is plugged in and change its settings. If you do not see that, something may not be loaded correctly.
Since you have an extra card, there may be extra settings you need to check on a Sound Blaster mixer. I have not used an external card with Windows 7, so I have no experience with that.
If you have a computer with front and back plugs, both may not work.
Just so you will know, many folks have had problems using a microphone with sound recorder. It usually works, but the input volume is normally very low.