USB v FireWire

[Bob Alexander]

Sorry for the lack of snips, but on that theme, as an ABSOlute newbie 
tech-wise (and oldie music wise):

I bought this G4 tower last year, instead of an imac, because it has a 
PCI slot, which I was told was better for audio.

  I don't really know what a PCI is, or what the slot looks like, or if 
I do, indeed, have a 'sound card.'

  Starting there: in OSX, !) how do I find my 'sound card' and later 2) 
what is the 'best' way to get started, as in. getting a mic plugged in.

BobA