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Comment about what we have already said !
Are you trying to install XP by booting the computer with an XP CD ?
- is it a regular Microsoft CD, or an XP Re-installation CD for another brand name computer model ?
If it's an XP Re-installation CD for another brand name computer model, you probably can't use it when your model is different !
- if the bios Setup Boot Order or similar settings are set correctly, you should have seen "Press any key to boot from CD" or similar early in the boot sequence, and you press a key while that line is on the screen to boot from the CD.
If you did NOT see that line, you are NOT booting from the XP CD.
STOP: 0X0000007B = INACCESSIBLE_BOOT_DEVICE
The stuff in the brackets beside that is usually specific to your own computer and useless regarding searching the web with the stop error and the stuff in the brackets. .
If you search using: STOP: 0X0000007B
you will get lots of "hits" and lots of possible causes.
A possible cause - the NTFS version Vista and Windows 7 uses is slightly different than the NTFS version used for XP and below. I know from experience Vista and Windows 7 can recognize a NTFS partition that was made in XP or below fine, BUT XP CANNOT recognize a NTFS partition that was made in Vista and Windows 7 fine !
If you can boot using the XP CD, DELETE the existing Windows 7 partition(s) before you do anything !
As in - let the initial files load from the CD, proceed to Setup, DELETE the existing partition(s) on the hard drive.
Then you should be able to make one or more partitions and format it / them fine.
(If Setup finds no (SATA) hard drive, then change the SATA controller(s) mode in the bios to an IDE compatible mode - see response 2.)
When you have only one hard drive ....
Windows Setup defaults to making only one partition on a hard drive (or, a brand name software installation usually has only one visible partition on the single hard drive).
The problem with that is if you ever need to re-load Windows (or the original brand name software installation) from scratch, you lose everything on the partition Windows was installed on, and when you have only one (visible) partition on the hard drive, that's everything on the drive - unless you copy the data you don't want to lose to elsewhere BEFORE you install Windows from scratch (most people don't bother, and lose all their data) .
If you're installing XP from a regular CD, it's recommended you make at least TWO partitions on the drive.
How to make more than one partition on a hard drive, when you're installing Windows on a blank hard drive, or when you are deleting the existing partition(s) on a hard drive before you run Setup .....
See Response 3:
In Vista and Windows 7, you have the option in the operating system itself (in Disk Management) of shrinking the original one visible partition to make un-allocated space available, which you can software partition and format to provide another partition (or other partitions) on the same physical hard drive.