Downgrade win7 to winXP

First, this isn't for me, it's for an elderly family member who's running on an old rig. They purchased win7 from a retailer after being advised to upgrade, which is fine if they had a decent system. They don't and as such win7 runs very slow.

Anyway, I come to re-install winXP for them and every time on the installer, just after it's about to load into the process (after it's done with the initial driver loading) the PC just goes into the good ol' blue screen of death.

I can't seem to get around this and I really need to sort this out for them as they only use the internet which runs completely fine on winXP for them but not with win7 because of the additional RAM usage by the OS.

Any help would be greatly appreciated.

Is your blue like one in this tutorial?
SATA Drivers - Load in Windows XP Setup on Dual Boot

theog said:

Is your blue like one in this tutorial?
SATA Drivers - Load in Windows XP Setup on Dual Boot

Nope, it's actually close to this sort of image (I did a quick google image search)

Before that screen, I get the normal winXP blue loading screen with it loading the drivers in the bar on the bottom. Just as it gets to the point where it's loading windows, it crashes out to the blue screen of death like the one above

Check your HD.
Disk Check

Check with a hard drive diagnostic tools.
Hard Drive Diagnostics Tools and Utilities (Storage) - TACKtech Corp.

I did the disk check (no errors) and the WD Diagnostic of their drive (no errors)

You could also check out the memory using Memtest, but first and foremost, you should write down the exact error codes from the BSoD. Without those, we can only guess blindly. With those, we can pinpoint exactly what's wrong.

Look in the the C: drive root to see if there is a windows.old folder, as you might be able to roll back to XP using that: How to restore a Windows 7-based computer to a previous Windows installation by using the Windows.old folder