I am wanting to build a small as possible subwoofer for a home computer.

My choice so far is Cerwin Vega makes a 4" and a 5.25" 2 way which makes decent bass for this size. Has anyone done this before and if so with what results?

What size box would one use also? I am thinking a sealed box of .10 cu ft or so would work but don't know of an exact formula. Also does anyone have any idea of the amount this small of a speaker displaces. I am guessing .005 to .010 cubic feet.

Thanks in advance for any and all help.