RAID1 is basically a mirror of the original disk.In this article i will be using these terms :-
1) Original HDD -> The default Disk on which your server OS is currently on.
2) Clone HDD -> Cloned from the original Drive
3) New Drive -> the one you have decided to make a raid drive.
3 drives of equal size (i am using 160GB x 3 drives)
make a copy of your original hard drive to another drive which we will call the "Clone HDD", you can use
many tools to clone your drive like bartpe, easeus disk copy, etc.
after creating a clone HDD from the original drive, remove the Original drive and only use it as a backup (if things get screwed up and you don't have a backup... :D ... you can rely on the original HDD to save your self.)
You have to convert the Clone HDD into dynamic disk to. right click on disk and select "Convert Disk to Dynamic"