How do I know which one is bad?

Here's the message I get on boot.
http://i242.photobucket.com/albums/ff157/jpete71chevmal/sataerror.jpg

And after I boot, I get this.
http://i242.photobucket.com/albums/ff157/jpete71chevmal/sata-1.jpg

Sorry that picture is so big but it was illegible any smaller.

I should have expanded the red "!" in the upper left when I took the picture. I did it afterward and it showed both drives and one of them had a red icon on it. It looked maybe like a lock or something.

Any help would be appreciated.

See if there's any utility on the Seagate site (http://www.seagate.com/www/en-us/) that can run a test for you.
Probably listed here (http://www.seagate.com/ww/v/index.jsp?locale=en-US&name=downloads&vgnextoid=51e092db8a13d010VgnVCM100000dd04090aRCRD ).

Reboot you computer.... Go into Bios.
In the bios you can run a diagnostic on your disks. The diagnostic will give you the serial number of the disk. Match it up and you are good to go.

Big D

See if there's any utility on the Seagate site (http://www.seagate.com/www/en-us/) that can run a test for you.
Probably listed here (http://www.seagate.com/ww/v/index.jsp?locale=en-US&name=downloads&vgnextoid=51e092db8a13d010VgnVCM100000dd04090aRCRD ).

I have "Seatools" which is listed as the diagnostic software. It gives me an error. "Fatal Error: Device Discovery....Not Found Void Initialize()"

If I expand the red "!" in the second picture, it lists the S/N of both drives. Should I just assume the one with the red icon is the bad one?

What would happen if I picked the wrong one? It would just be unbootable correct?

Have you actually installed the raid driver before booting windows?

Judging from his previous post (http://www.chevelles.com/forums/showthread.php?t=275841) ,he's got RAID setup but 1 drive's giving error's

I have "Seatools" which is listed as the diagnostic software. It gives me an error. "Fatal Error: Device Discovery....Not Found Void Initialize()"

If I expand the red "!" in the second picture, it lists the S/N of both drives. Should I just assume the one with the red icon is the bad one?

What would happen if I picked the wrong one? It would just be unbootable correct?

Most probably yes :), there could even be a small synchro failure and maybe they still both boot :)

Well I "synchronized" the drives and everything seems fine. What would cause the drives to be out of sync? Sectors going bad? I did some searching around and I guess if the two drives aren't IDENTICAL it will give this error. But I didn't find any warnings that the drive might be going bad.

Also checked both drives's firmware?

Try resetting the cables to both drives.
Sometimes it just vibration that loosens the connections and gives a false error .