Hi I have a Seagate Cheetah 15k SCSI drive with LSI Logic Controller. It won't boot up. I have installed the drive in a windows XP PC and I can see the drive in Disk manager but it shows unallocated disk space. So that means that the partition is missing or corrupt. The drive was running Win Server 2003. I would like to repair the partition.

Unallocated disk space means that the file system is corrupted. You could try to access the data using a Linux Live-CD - they access the data directly and are much more tolerant of NTFS file system errors.
You could also try this http://findandmount.com/ It has allowed me to access data that even some Linux distro's deemed irrecoverable. But beware, this is a program with problems - you can format the partition by accident very easily; be careful at what you do, don't click on something unless you are absolutely sure.
Either way once you have access copy the files immediately.

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Try to format the drive from the disk manager then try to install XP again.

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