Markk, I have this set up with no problems:
HD 2 Accel
G5 Dual 2
1 gig ram
160 gig sata drive system drive
160 gig 7200K internal sata Pro Tools drive
192 i/o
External firewire enclosure:
http://www.newegg.com/app/viewproduc...155-205&DEPA=1
with a Seagate 75 gig HD.
Not sure why yours doesn't work.