Thanks. I mis-quoted the mac as mid-2009. It's a late 2009. I checked the serial number; seemed to indicate I was on the early edge of 'acceptable', but point well-taken. I actually did exactly what you recommended. The installation and back-up recovery is proceeding currently. Thanks for the reply- I'm hoping it works! I back up daily, so thank goodness i can do a full restore if absolutely necessary. I just haven't used the disk utility much, or the OSInstaller options, so I'm trying to be cautious.