Well, to be simple.. the equalizer does the same thing as the system in ur car equalizer did..
it allows you to change the sound of the cd being played..
Like open winamp.. it has a built in equalizer.. its kind of like that..
when you buy one for your comp it allows you to have certain inputs in to the computer so you have better sound quality.. Like it uses an RCA jack instead of a head phone jack to the speakers..
It will also allow you to use Digital instead of that Analog stuff, digital will sound muuucho better..
http://www.essencompu.com/icywebstorefront.asp?ID=4&sID=43check out that site.. its got some gooda stuff there..
a nice cheap equalizer for the PC also.
and I noticed you said you had a system in ur car? w00t.. what Kind?

I had 2 systems.. they were cool.. JL audio 12inch w6 subwoofer,
and my last system was a 12inch Mmats Juggarnaut sucka 0wned..
Now my car is running 2 6x9's lol..
I had a 1600watt amp LEgacy it was crome.. I loved it..
but yeah anyways.. You can hook ur system up to your computer with the equalizer..
You will still need to power it some how.. I cant think of what its called.. I know radio shack has it.. and you can ask for it..
but you have to make sure u get a DC current one.. or u might ruin ur speakers..
Hrmm.. thats about it d00d
g00d luck happy Moddin
l8rz