You can download the drivers for the XP installation of the laptop here:
http://h10025.www1.hp.com/ewfrf/wc/s...roduct=3675083
However by the looks of it, it may be difficult to get it installed in the first place. You have a SATA hard disk which is why the XP setup cannot detect the hard disk, as the XP installation starts it will ask you to press F6 to install a mass storage device driver. At this point you would usually press F6 and insert the floppy disk with the SATA driver on it.
Problem No.1 - No floppy drive, you will need a USB one (for simplicity, there are other options)
Problem No.2 - There doesn't appear to be a downloadable driver for the SATA driver on the website that will fit onto a floppy disk. There is an Intel storage driver installation file avaliable, you may be able to extract the OEMSetup.txt file from another computer and copy the drivers to a floppy.
Problem No.3 - Windows vista home premium does not give you a downgrade path to Windows XP, you will need to buy a copy of XP. Also from a licensing point of view, you will need to buy the full retail boxed version rather than the OEM version.
If you knew that you were going to need XP you really should have bought one of their laptops which has Windows Vista business installed, you would then be able to downgrade to XP with far less hassle and no cost.