I've just downgraded to WinXP Professional (SP3) from Vista. Install was to a brand new Caviar Black 1TB drive. My machine has eSATA connectors on the back and on the front. I have a XION eSATA HDD dock (XON-SAHDCB-COMBOCR) that was working fine under Vista Ultimate. The eSATA connection is not being recognized by XP at all.