Your problem is at least two fold, the first issue being that trying to record your band through a soundblaster card it will be extremely difficult to get good recordings these cards are simply not designed for this use. You would much better off getting a dedicated audio interface like these [[url=http://[/URL]="http://www.sweetwat…"]FireWire Audio Interfaces | Sweetwater.com[/]="http://www.sweetwat…"]FireWire Audio Interfaces | Sweetwater.com[/] which are firewire there are also USB units.

Bleed is a seperate issue and is frequently dealt with by some of these methods:
Close micing
Utilizing the null points of mics
Dividers/GOBOs
Greater distances between sources

I think given your present understanding of recording that going into the studio is a good idea. You will certainly achieve a better product while being able to concentrate on music and at the same time learn a goods deal about recording

and just to add to what JG has to say:
high pass / lowpass filtering and gating will also alleviate some bleed
as well as the obvious overdubbing.

If your planning on getting something done soon, I agree with jg. Not having any experience recording, you're going to run into all kinds of frustrations in trying to get the sound you want. You may end up spending months on the project and still wind up going to a professional anyway. Going into a studio would not only yield a better and probably quicker product, but you would also learn a great deal about recording as well, which would make you more self sufficient in the future.