Disk format error or user security denied

By default disk format, win2000 use NTFS, winXP use FAT. They can't read each other.
link C drive to another computer that use NTFS (Vista or XP that installed with NTFS format), then you should be able to read it.
Another posibility: NTFS support user security. If the drive was protected under a user account, then, you have to fix the win2000 and login as the same account ..