Thanks for the help.
I ran the disk utility & got errors on "verify disk" & "repair disk" (permissions were repaired though). I also ran the AHT and everything passed.
I took it to an apple store and the HD mounts when booted from an external drive but I get an error when trying to reinstall os x. also got an error when using diskwarrior to try and fix the HD...
So it looks like i have to boot externally, back up what i can, & get a new HD.
what a pain!
anyway, thanks again.