What New Mac To Buy?, for ProTools 24 Options

[zeze]

hi all!

I have a 9600/G4-450(XLR8) which I use with a Digidesign d24 card, I also use NI instruments so often the cpu gets overload; I'd like to buy a new Mac but I'm not sure which model suits best my needs.
For MIDI I use MOTU MTP AV(serial) and I'd like to know if it's ok using it with a Keyspan USA-28x adapter or someone suggests to buy a new USB interface: which is the fastest MIDI system?
Also I have installed an internal scsi accelerator card ADAPTEC 3940UW for ProTools hard disks; it's still worth using it on a new Mac?
How much RAM do you suggest for the new Mac?

thanks a lot
zeze

[Bonitap]

I've had no trouble using this Keyspan serial adapter for USB on my PowerBook G3, with MIDI In and Out to my interface. Going this route for a year saved me money.
Bonnie