sequencing external keyboards with 002

[rmpc2500]

im expieriencing serious latency when sequencing outboard keyboards with 002 running on a single g5 with 1.5 gig of ram, i've tried to work with low latency monitering on but then i can't use any plug-ins such as my click track and still the latency exist i've tried running all audio of an external firewire hard drive like digi suggest with le system and that didnt help, i use to have a mbox on os9 with a g3 ibook with a motu usb midi interface and didnt have nearly as much latency . this problem is driving me crazy please help!!!!!!!!!!!!!!!