Audio I/O Interface and Other Newbie Questions

[Steve Shapiro]

Hello all,

I'm pretty new to the world of computer-based music recording, so I 
hope my questions below aren't too naive. Just to give some background 
first, I have a MDD Power Mac G4 dual 1.25Ghz running Jaguar and I have 
just ordered a copy of Cubase SX (it's due to arrive tomorrow, in 
fact).  My end goal is to make multitrack recordings and master 
everything to CD (i.e. I want to make homemade albums of my own music). 
My basic tracks will be MIDI-based and then I'll overdub live vocals, 
guitars, and miscellaneous other sounds.

Now that I've gotten that out of the way...Here's my questions:

Given that the bit rate of an audio CD is 16-bits, what's the reason 
for getting an audio I/O interface that lets you record at 24-bits or 
more?

On a related note, does anyone have an opinion of the Midiman 
Audiophile 24/96?  It features 24-bit 96 kHz multitrack recording 
(hence its name).  If I'm planning to run Cubase SX on a MDD G4 dual 
1.25GZ machine, is this card overkill?  Why or why not?

Finally, I also have a PowerBook G4 Titanium 500Mhz running Jaguar.  Is 
there any chance of doing all my Cubase SX recordings on that?  If so, 
is there any audio I/O interface cheaper than the MOTU 828 that will 
still give me similar high-quality/low-latency results?

Thanks in advance for your help and advice!