Turns out that re-installing the Mac OS was a breeze. Now however, I have to update everything again. The Mac OS X update alone is over 140MB. Strange -- with files that big, why can't you update in stages? If you stop the download halfway, you have to download the whole darn thing from scratch.
And my trackpad's still not working, so I may have to go to the service centre anyway. I personally don't like using trackpads, but it was convenient.