Hi, @IT_WinSec
I am just answering the person's question on how to get XP installed, which can definitely be done.
I did not reply to discuss the merits of installing XP. Personally I agree with you, but that is his decision to make, not ours. That was his original question, was it not?
You can use all of the XP drivers from the HP Probook 4545s on the g4 with the exception of the BIOS and firmware files.
The audio is going to be problematic to get to work.
https://support.hp.com/us-en/drivers/selfservice/hp-probook-4545s-notebook-pc/5229461
@Triton_Prod
If your XP experiment does not meet your expectations, and/or you want to install W7 x64, you can use all of the drivers and software from the g7z-2100, except the BIOS and firmware files.
https://support.hp.com/us-en/drivers/selfservice/hp-pavilion-g7-2100-notebook-pc-series/5262610/mode...
In addition to the above W7 drivers, you will need to install the amd chipset drivers.
Download, and run the amd chipset drivers from the link below, and restart the PC. You want the 1st file listed on the webpage.
http://support.amd.com/en-us/download/desktop/legacy?product=legacy4&os=Windows%207%20-%2064