XP does not have the drivers required for SATA until it is booted. Which is why generally people say you can’t boot XP from eSATA. However, some posts on different sites seem to indicate it is possible if your motherboard has a native eSATA slot(mine does, ASUS M2N32-SLI Deluxe), and some suggest you can alter the boot order so that the SATA drivers get loaded before XP. And yet others suggest if you have a good BIOS it will work.
Can anyone offer some clarity to this issue?