Killall

Need Opinion Between 3 Systems

Sorry, title said 3, but is actually 4 systems.

Hey everyone, I have the availability between the following four systems to start creating my home studio with and I wanted to see what you guys thought.

System 1 - iMac G4 1.25Ghz 256MB 80GB, 20 inch screen, Superdrive
System 2 - iMac G4 1.25Ghz 256MB 80GB, 17inch, Superdrive (Lamp)
System 3 - PowerMac G4 1.25Ghz 256MB 80GB, Combodrive, 17inch display
System 4 - iBook 1Ghz 256MB, 60GB HD, Combo, 14inch display

I realize that any of these I'll have to throw more RAM into. I'm leaning towards the iBook so that I can record live and have the portability, especially since my band is in a practice studio away from housing. However I know it only has 1 memory bank so the most it could have is 640mb of RAM.

I'm completely new to Mac and this will be a big learning experience for me.

Any suggestions?

P.S. It's these 4 systems or nothing because of a program I have where I am employed.

Ok, Total Newbie Question About Setup

Currently I'm a musician, however how never done any recording or anything computer based at all other than going into the studio and the engineer does his magic while I explain the sound I'm looking for, etc... while I just play. I'm looking to change this via all the greatness I hear around mac in the music world.

My question specifically is around usb-keyboard that i will begin my experimenting with. Looking on the apple site I saw this:
Edirol PCR-30 MIDI Keyboard Controller for $199.00. Is there something better for the price I should be using?