this little site seems to have some nice information.

Havent read through it all, but from what i can remeber a friend of mine told me a while back is that RAID's need to be set up then data put onto them.

Im not sure how valid/safe it would be to install XP then try and add another drive and forcing them to be a RAID.

Just out of intrest would you set the RAID up where one drive is a constant real time backup of the other, or set it so that the OS would see the 2 drives as one big drive?