i HAVE A GATEWAY WITH 2 500 GB SATA DRIVES; I HAVE VISTA AND MY PROGRAMS AND DATE ON ONE OF THE DRIVES IN TWO PARTITIONS. cAN i SET UP THE RAID 1 WITHOUT REINSTALLING EVERYTHING AND HAVE THE FIRST DRIVE MIRRORED ON THE SECOND?
No.
Well let me rephrase a little, it will if the controller supports building a mirror from an already established disk.
Most will not.
Why do you want to run RAID 1?