Replacing all hard drives on SBS 2003 server?

Being the network admin I’m almost ashamed to be asking this, but… my Win SBS 2003 Standard server is running out of disk space quickly, and unfortunately my only option besides adding an external drive is to replace the 2 hard drives currently installed on the server. They are 2 120GB drives installed as a RAID 1 setup, and I’m planning on replacing them with 2 500GB drives. I was thinking some sort of ghosting program, but wanted to get some opinions first. Any help people??