If you get a hard disk great than 137Gb you have to enable large hard disk support. Eventually figured this out installing my hard disk today. There's a
registry key you have to enter named "EnableBigLba" in the ATAPI service if you have anything less than WinXP SP1. You should also install the latest version of the Intel Application Accelerator (currently v2.3) if your motherboard uses an Intel chipset. Anyway, one of those changes fixed it. I'm now reorganising all my files.