Having problems installing vista to zif hdd.

I have finally got my ZIF HDD working, and having run Vista on it, it actually runs really fast.
But as I love OS X these days, I want to dual boot the two.

I was having a fair bit of trouble installing either, but then finally got OS X installed, partly through sorting out the ZIF cable so it isn't squashed (that seems to cause a problem with my particular drive) and imaging the OS X on my external HDD onto a partition on the internal HDD, then totally reinstalling it.

But! Vista will still not install. Either to a totally clean HDD, or to my current setup which is 15GB OS X Extended (Journaled), 15GB free space (to be formatted NTFS for Vista) and the remaining roughly 25GB formatted as FAT so both OS X and Vista can read and write to it.

i am installing from an external DVD drive, and using a vLited Vista Business which I have installed successfully to both the SSD and my current ZIF drive.

It boots fine, gets to the step with selecting drives, and I can format either of the existing partitions, delete them or add a new partition in the free space.
I format the free space with NTFS and its 15GB so well enough for Vista.
But the installer says "Windows cannot be installed to the selected partition. Please ensure the disk's controller is enabled in BIOS"

But it obviously is enabled because I can boot OS X form it.

Any ideas to help?

Rory