Hardware :: Corrupted Drive- Mechanical Or Logical - Fsck Repair?

I was working on my RHEL 5.2 workstation yesterday when the OS became flakey. first I noticed that some software that I had running was outputting and error that it was unable to write to log file because permission was denied - I've never seen this output before- it would have been writing to my home dir running under my user name. From an open terminal, i did "ls -al" and saw that many of the permissions the files in my home dir were listed as "????????" some were still "rwxrwxrwx", as well, many files were highlighted in the colors set for links and root privileges.

I tried to start a new terminal, and it failed. then Gnome crashed. When I reset the Machine, I got through grub, and into the startup, and after finding the Volumes, the startup failed with a Kernel panic:

giving several errors- like:

I dont have much experiencie with this stuff, but it looks obvious that somethig like the MBR or wherever the partion information is stored might have been corrupted.

What I dont understand is why I can get into GRUB (its a dual boot Windows Vista, RHEL machine). I'm guessing that this means its not a mechanical problem, because I can get RHEL to begin to boot which i think is failing somewhere around the /etc/rc.d/re.sysinit script, and also can get Vista to bring up the inital windows screen and a mouse pointer on spanning both of my screens which i think means that it must have at least loaded my ati drivers for my dual head radeon 4850. windows hangs there however.

I've tried the RHEL 5.2 rescue disc, and it doesn't recognize any Linux partitions.

I ran the system diagnostics out of the dell bios and it came back with a failed HDD : Error code 0142, but from digging around a bit I've found that this is a very broad diagnosis.

My concern over it being a mechanical problem is that I'm not sure that I want to try to run any further diagnostics, or any of the disk utility programs that i've seen listed here on linuxquestions, as it might damage it further, and there is some data that i would really like to get off this disk.