Good point Mike -- I should've mentioned the hackintosh aspect of cheap PCs. Build a cheap PC and install OS X on it... have your cake and eat it too.

Lifehacker's got a great tutorial on this for anyone who's wondering:

How To Build A Hackintosh With Snow Leopard, Start To Finish

Uh, yeah dude.

Thanks very much Raafi -- very helpful! The real reason I posted this, of course, was to find out about good apps I don't know about, and now here are three. Anyone else?

That was my first instinct, too -- but in video mode the mechanical shutter stays open and the DSLR uses an electronic shutter instead. So in fact a three-minute shot would be no worse for the shutter than a single 1/200th still shot; basically, in either still or movie mode, a shot is a shot.

To update: it's a full year later and the noise has finally returned (albeit in a different, quieter form). I'm going to try the repair with some silicon lubricant or graphite when I get a chance.

It's true that WD-40 likely isn't ideal. Just to update, however, it's 9 months later and the noise hasn't come back.