First thing in the morning, I went to the computer shop to claim the replacement of my exploded power supply. And I was lucky enough to get it. Unfortunately, they didn’t have the 520 watts model anymore, so I set with 480 watts.
Lev was kind enough to come and stop me from doing yet more stupid things like killing myself via means of electricity. Power supply successfully installed, hard disks rearranged, and most of the staff works, apart from problems related to root.root ownership of all files. I’ve decided not to touch anything for another day, so that I could go one step at a time. :)