I know bugger all about PS3s, but what sort of drive does it use? IDE? Fast IDE? SATA?
Get youself an appropriate external drive enclosure, stick it in that, and use the USB port on your laptop or desktop along with a free download copy of Macrium Reflect to save a complete restorable disk image to somewhere else. (Well, as long as you're comfortable with opening up a device and removing a drive.)
A lot of experience I've had with corrupt operating systems on my customer's data acquisition PCs stems from wrecked or corrupted system files, which are required for boot up, but it tends to leave all the data (non-OS related) untouched and accessible if it's read as an external drive.