Let me preface this by saying that my old, generic Soundblaster PC soundcard had a "stero" input, but it shure worked as mono when I used it. Hopefully, you've at least got true stereo input on yours.
I assume, from the phrasing of your question, that you want to record at least two stereo/four mono tracks at the same time.
As long as you're using a 1-input soundcard, you're stuck only recording one stereo channel of audio at a time. This will allow you to record two mono tracks simultaneously, such as a vocal mic and a guitar mic. You just can't exceed that limitation with your current hardware.
There are many audio interfaces on the market that will allow to you to record more tracks simultaneously, but you can run into big money that way. If you're after quality sound, you'll probably have to get a better audio interface anyway - vanilla sound cards just don't do it for most recordists.
I use a Lexicon Omega, which has 4 ins, 2 XLR ins, and a couple of outs. Its USB, and it keeps me happy, but I only record one part at a time in my studio. That type of thing may work for you, but it costs about $300.
Check out
http://www.zzounds.com/a--2676837/cat--Audio-Interfaces--2418 to get a feel for your options, but come back to the forums and ask for specific opinions once you know what you generally want.
Hope this helps.