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#1030
What is the necessity of having a copy of DISK0 partitions on DISK1? If you need to backup an image of Win7 from DISK0 I would use Win7 backup imaging to save it to an external HD or a single partition on the right end of DISK1 which you create NTFS Primary for that purpose: Backup Complete Computer - Create an Image Backup
Then I would unplug DISK0, set DISK1 as first HD to boot in BIOS setup, boot the XP install CD, see if it will detect DISK1, delete the first two partitions, create a New partition there and Full Format before installing XP as desired.
If XP installer won't see DISK1 to install, it is because it doesn't have the SATA controller necessary. You can insert it at F6 prompt during initial driver-loading phase if you have a floppy drive. If not, you'll have to slipstream the SATA controller into XP installer using this method: SATA Drivers - Slipstream into Windows XP CD
Once XP installs and starts up, power down to plug back in HD0. Set the preferred HD as first HD to boot in BIOS setup, then boot the other HD as needed using the one-time BIOS Boot menu key.
I know you have another thread going somewhere here now, but I can't remember if you were asked if you've considered running XP virtually using Virtual Box, Virtual Player, etc. Or have you tried to install XP programs which are balking in Win7 using Compatibility Mode?