How to install xp next to vista without cd or floppy drive on sata

Hi all,

I tried to install Windows XP on my Vaio P with Vista preinstalled. I need a dual–boot system Vista XP. Since the Vaio P has neither CD nor floppy drive, I used Nlite to integrate SATA drivers into XP package. However, it is all the same, looks like windows installation just ignores the newly integrated drivers: after copying files to installation folders and rebooting, computer throws the same hardware configuration error. I make a recovery of Vista bootloader with Hiren's Boot CD tools on USB flash, but it doesn't help. The only remaining choice is to recover system from the hidden recovery partition, what I have done, maybe, 20 times over the last two weeks. I also tried to hit F6 during installation to install third–party SCSI or RAID driver (I had put the SATA driver on the USB flash), but setup only looks for a floppy or CD...

What do I do wrongly and what should be done differently? Would highly appreciate anyone's help... My email is darius.kaunelis@takas.lt