I just put together my first system a few days ago and I was unhappy to see that Win XP Pro only recognized 137 GBs of a Western Digital 200GB SE drive. I checked out Western Digital's website and it basically referred me to Microsoft's and my motherboard's website (Asus - P4G8X Deluxe). I learned I had to edit the windows registry to enable 48-bit logical block addressing and make sure the motherboard's BIOS would support 48-bit Lba.
Part of the microsoft article states that enabling support for 48bit address could also result in data loss and that SP1 should be installed for WinXP. For Win2K requires SP3 installed. Probably needs to be slipstreamed and then installed.