A lot of times on machines like these the Recovery partition is still accessible even when the hard drive has gone bunk (unless it's physically clicking, head stuck, platter damage etc). If you hook it up to a different machine, give the recovery partition a drive letter, and find the Vista .WIM file, you can use a tool such as ImageX to apply it to a new hard drive, of course you'll also have to make that drive bootable via diskpart, make it active, and possibly run tools such as bootrec and bootsect. Good luck!