What you need to do is upgrade your IDE controller to a >137GB model.

The Promise range seem to be amoung the best out there and it will co-exist with your existing (on-board) IDE controllers.

The Promise's controller has its own BIOS to give full access to all the drive capacity, even for boot support.

Try This Link for more details.

I don't know about local agents in OZ but I can buy the Promise controllers here for about $NZ70 or less for the "basic" model [so you should pay the same in $AUD once GST is factored in].

If you want me to source one for you and post it over I can do that.