200n - how to set SATA drive as slave. PLEASE help

How do you set up a SATA drive to be a slave to an IDE drive?

Running a 200N with latest bios.
My original setup was a 200n with a samsung spinpoint 160GB HD, formatted as NTFS, booting into XP Pro.

All was fine for several weeks until I installed some dodgy drivers which made my XP installation unbootable, even in safe mode.

So I put in an IDE HD and installed XP on that. That works fine when the SATA drive is disconnected. However whenever the SATA drive is connected, it takes over midway through a boot, leading to repeated reboots. I have set up the boot sequence to be 'HDD 0' only. I do not see anything in the BIOS to set the SATA drive as slaves.