You can install windows on a single RAID1 array and keep data on it also no problem. My advice, during installation partition the array into two partitions one for data and one for the OS. Both will be mirrorred. Note, if you card is a Promise card you'll find there is no driver support for Windows 2003 and have to install the XP driver.
<A HREF="http://www.anandtech.com/myanandtech.html?member=114979" target="_new">My PCs</A> :cool: