Fit them to USB Caddies and backup immediately before you even begin to look for problems.
If the drives can not be recognised in a unit running XP you are in real trouble and you'll need to find out who the bright spark who didn't think that any Backup where important and point out to them that they have just lost the entires companies Data which is going to cost thousands to recover.
If you can read the HDD/s just copy the data across to some external Media and save it if you are unable the read the HDD/s then pack them up and take or send them to the nearest Data Recovery House who is capable of recovering data off dead HDD/s.
While the HDD/s are away being recovered you can rebuild your 2003 unit and wait for your data to come back so that it's usable. But I would run some Diagnostic tests on this unit with the Ultimate Boot CD available for download here
http://tinyurl.com/3jnpy
Then after you have made sure that everything is working properly run a Live Linux on the system just to make sure that it will actually boot there are quite a few available from here though Knoppix would probably be your best option
http://tinyurl.com/23nmq
Col
