Opening up the HD is a very, very bad idea. HDs are vacuum-sealed. A very popular comp show mod was to have windows on your HDs. These worked great for the show, but died a very rapid death because all kinds of dust and microscopic particulates got in, both when you had the drive open and when it was just sitting in the case. Basically--and here's where you should be interested--these drives made a rapid Clickity-Click of Death noise.
These window'd HDs and their untimely demises were why a bunch of people had a total nerd-gasm when the Raptor X hit the market in all its clear-panel glory.
I would try the controller swap if you think you can pull it off. But the moment you get that thing working, you should already have another drive to immediately back up EVERYTHING YOU CARE ABOUT. Do it manually, and do the most important stuff first. You might only have hours. Maybe less. Once that drive starts spinning and Windows loads, get on it, don't take a break, and know beforehand what data you really want, and have the location written down.
With a little luck, you might just pull it off. If you do, go out and buy an external HD, and back up once a week.