You can install XP to your laptop!
You will have to change some bios settings before proceeding,
Before you do so, you will have to backup all your data to an external hard drive or to another partition,
Then Restart your laptop, access the bios press F1,
You will have to change the sata mode to IDE or change any related sata options
Insert your Windows XP disc, and just change the boot type, to DVD
Save and Restart your machine
Follow the instructions, you will have to format the Windows Vista to install Windows XP