i have sony vaio vgn cs36gj laptop which came with Vista.I inserted my genuine XP CD in the DVD drive and started the system.... Everything appeared to be working as it does when you are installing XP on a new machine UNTIL i got a windows which basically said that
a problem has been detected and windows has been shut down to prvent your computer
if this is the first time you've seen this stop error screen restart your computer
Do yourself a favor and don't remove Vista. It's a better OS.
same problem with my laptop. Sony people tell me that Xp require sata drivers wich will be install while Xp installation. via USB Folppy drive. for more details contact on my mail address.