Large Drive Formatting in XP or 2000

To see a larger size hard drive >137 GB in Windows 2000 you must have SP4 installed and the EnableBigLba flag set to 1 in the registry...

http://support.microsoft.com/kb/305098

For Windows XP, you must have SP1 installed with EnableBigLba set to 1...

http://support.microsoft.com/kb/303013

Both O/Ss expect a 48bit LBA-compatible BIOS.