I'm only using 1 200gb SATA.

The reason why I've mentioned it is because I read that you should disable it if its not being used.

When I can get to the install, it lists the drive as being about 130gbs which I believe is due to it being the original XP Pro (with no SPs) but its certainly there.

If I select it it informs me that the drive already has an operating system on it and multiple installs could be unstable etc. Replacing the operating system on it has the same effect.