Hi there, if you are using Windows ( I assume you are) do the following.
Click Start --> Settings --> Control Panel --> System
Once on the system menu click the Device Manager tab. Scroll down to Sound/Video/Game Controllers. Open up the list and voila. Those are the sound cards installed on your system. If you want to find out more info about them highlight a device and click Properties.
You'll find as you read this board that conumer grade soundcards are generally frowned upon. I however still use a cheap Ensoniq Audio PCI and make it by so don't worry about having a cutting edge sound card if you are just starting out. Hope this helps...
Oh one more thing... 99% of sound cards made today are full duplex so I doubt you have to worry about it.
-valgrim