A Really Bad Nightmare, LAP gradually decreasing in performance Options

[chili]

HELP!!,
i am having major problems with logic audio 4.7.3(yes,yes,i know i should have made the upgrade to at least 5 by now-will soon- but is a question of dollars.)

i used to be able to run up to 48 audio tracks with up to 40 plugins going without a hitch, but over the last couple of months this performance has gradually decreased to avrage out at 15-20 audio tracks and starts stopping after just a few plugins(like 1 x autotune,1 x voxciter,,2xcompressors and a few fat eq's) i am running oS9.1 /G4 450mhz/512m ram/10g hd internal(for apps)30g internal hd for audio and an external momobay 120g firewire for backups. with a digi 001 as my audio interface and a motu midi interface.i defrag my drives weekly and run nortons regulary as well...am completely stumped after doing a total reformat of drives and clean installs of my oS and Logic software
can anyone help???

cheers,
simon.
also a secondary thignyprob noit in this topic but--i cant get a digital signal in from the digi 001 to logic audio-they dont seem to talk to each other that well any clues for drivers or extensions??