Unfortunately for a RAID 0 array, all data on both disks will be destroyed. Then you will need to reinstall drivers and then windows. Sorry dude
But, for a RAID 1 Array you don't lose any of your data. The Data on your primary disk will be mirrored on your "mirror" disk. You use the CREATE & DUPLICATE Feature. (Yes you can do this with windows install on the primary disk. IF you want to destroy the data on both disks you use the CREATE ONLY feature.
Here is a good website that outlines what i'm trying to explain:
It is also a great guide to RAIDing with Windows XP. Bookmark this one, it's really good.