CQ40-115AU Support Windows XP

SATA AHCI for the AMD series format Windows XP you can use sp39719 for amd sata driver.
here:
http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=321957&prodSeriesId=3687621&prodNameId=3687622&swEnvOID=1093&swLang=8&mode=2&taskId=135&swItem=ob-61695-1

Extract it and use data from RAID7xx folder for amd sata driver.

or it would be the same files if you download from gigabyte site here:
http://www.gigabyte.com.tw/Support/Motherboard/Driver_DownloadFile.aspx?FileType=Driver&FileID=3676

Install .Net Framework before others:
http://tinyurl.com/758p8

ATI Radeon HD 3200 Graphics/Video Driver
here:
ftp://ftp.hp.com/pub/softpaq/sp39501-40000/sp39764.exe

or directly from amd site here:
http://game.amd.com/us-en/drivers_catalyst.aspx?p=xp/integrated-xp

ALPS Touchpad Driver
ftp://ftp.hp.com/pub/softpaq/sp25501-26000/sp25796.exe

Update your hardware using Microsoft update

MS UAA (required with a reboot before Audio driver)
here:
ftp://ftp.hp.com/pub/softpaq/sp33501-34000/sp33867.exe

IDT High-Definition Audio CODEC Driver (from Microsoft Update Catalog)
here:
http://www.mediafire.com/?vynu6uq4yzv

Unzip to a folder.
From Device Manager, right click "Audio Device on High Def Bus",choose Update driver,
No to connect,

Install from a list or specific location,
Choose search for the best driver in these location, Browse to the extracted folder.

Next - up to finish and Reboot.

Realtek RTL8102E Family PCI-E Fast Ethernet NIC
here:
http://www.radarsync.com/driver/d275761-realtek_rtl8168c_p_8111c_p_pci_e_gigabit_ethernet_nic

or (copied from Microsoft Update Catalog)
here:
http://www.mediafire.com/?ftlmac6jkmj

Other Devices ( Unknow Device )
Direct Application Launch Button

here:
http://www.c-tech.ac.th/ngology/BackUPDriver/Direct%20Application%20Launch%20Button%235/

P.S : download machine.inf and update all the unknow device will working ady , this system not importent to the Windows XP ! This device useing in Windows Vista only .... useing that inf file to update device and all unknow system will fix ady !!

Good luck.