@Priestly:
Thanks for your detailed report about what you have done and what happened.
Here is my comment:

1. The usage of my guide (= start post) requires an original (untouched) Windows XP CD with integrated SP3 as source. Since you used an already pre-customized XP ISO file, the integrated textmode driver cannot be found by the XP Setup (regarding the textmode drivers it looks only into the text file named WINNT.SIF dated 03/16/2010, which is within the i386 directory of your used ISO file, and disregards all later integrated textmode drivers).
   Note: Original XP Images do not contain a file named WINNT.SIF. Its presence verifies, that the related XP Iso file has been customized for an "Unattended" XP installation.
2. My Guide has been written several years ago and may not be valid for modern AMD systems like yours.
3. These are the main problems for users with an AMD system to get Windows XP properly installed in AHCI mode:
   • Missing universally usable AMD AHCI textmode drivers:
     The old AHCI compatible AMD RAID drivers named ahcix86.sys are fully compatible with Windows XP and can be integrated into the untouched XP CD according to my guide, but do not support modern AMD SATA Controllers, whereas the much newer AMD AHCI drivers named amd_sata.sys do support modern AMD SATA Controllers, but cannot be used with Windows XP from scratch (no appropriate textmode driver for XP available).
   • Original XP in-box ACPI driver doesn't work with modern hardware.
     Solution: Replacement of the original driver named acpi.sys by a modified one.

@tw2018:
Without knowing
a) which specific driver package you have downloaded and
b) which structure the extracted package has,
I cannot answer the first 2 questions. AFAIK only an "AHCI compatible AMD RAID driver" can be integrated into a Windows XP image.

Your question regarding the XP compatibility of your specific video card is off-topic. Please post it into a matching thread or start a new thread within this Sub-Forum.

@tw2018: Thanks for the requested details.
If you want to install XP in AHCI mode, the only usable driver from the ASUS list is the "AMD AHCI driver v6.1.2.5 for Windows XP 32 bit---(WHQL)".
Please give me the HardwareIDs of your on-board AMD SATA Controller (right-click onto it > "Properties" > "Details" > Property" > "HardwareIDs").

@tw2018:
Thanks for the HardwareIDs.
According to them I recommend to download, extract and integrate the "Universal 32bit AMD AHCI driver v6.1.3.35 mod+signed by Fernando", which is offered within the start post of this thread.
Good luck!

@tw2018:
No, the Certificate folder should not be integrated. It is only useful, when you want to install the related driver from within an already running OS.