When Windows encounters an error, the computers response is to restart itself.
Just for giggles, run memtest and see what happens. If that doesn't report anything, try booting up with only your master HDD (the one with the OS installed on it) in. Then one by one attach the other hdd's until it starts rebooting.
If the computer reboots with only the master hdd in it then you've at least isolated the problem to that one HDD. Try booting up in safe mode, and if that doesn't work, try booting up with a Windows Startup Disk. If none of these will work to get you into Windows, try turning off the automatic restart by rapidly pressing 'F8' as the computer boots up to access the 'Advanced Windows Options Menu.' Here you can disable the 'The Automatic Restart On System Failure' option. If you can do this hopefully this will get you into Windows to perform a System Restore; or produce an error message that is specific enough to diagnose your problem further. If you can get Windows to boot up by using any or a combination of any of these methods; you can try a system restore.
If none of this works your going to need to get your Windows CD and access the recovery console. First I would try repairing the Boot.ini file. It may even be that your entire boot partition has been corrupted. That would suck. Try the tips above before we go there though.
w00t my first post of the new year!
