Latency & Buffer Issues--motu & G4, need settings help Options

[cashmoney]

Hey everyone, I'm new here, and this seemed like the closest area for the subject matter, so here goes...

I have an old G4 dual 450 mhz, running tiger. I use it exclusively for DP 4.6. The audio hardware is a motu 24i based off of the 324 card. I am having really bad latency issues when tracking. I have to go to hardware driver setup and take the buffer down to like 64 just to make it tolerable. When I mix, I have to go back and reset it to 1024. My machine has 2 gigs of ram (maxed out) and I'm using 2 hard disks (one system, one audio data). My machine has tracked all 24 simultaneously without any problems, but when I try to record one track while playing back as little as 4 previous tracks, it tells me that the operation has exceeded playback capability. I'm new to DP, motu, and macs...this was just my first step towards a halfway-decent DAW setup. Is there anything else I can do to fix the problem? Cuemix is not compatible with a 324 system under OS X. Is there anything I can do without spending more money right now?