And contrary to your belief, it COULD have something to do with the storms. I assume you use an ethernet cable and card to connect to the internet, and if that's the case lightning could very possibly have traveled through that and fried your PC. Yep, you don't need to have it plugged in to get it fried. I've dealt with many computers that were fried via the modem or ethernet connection.
Nope, it was hooked up to the internet via wireless. Also, that night I turned off the surge protector (after shutting the PC down safely, of course), and unplugged it from the wall, so the monitor which was still hooked up to the PC was NOT getting electrical power.
As far as the power supply, yes, that's actually what first came to mind, due to the symptoms it showed (the flickering power light), but I wasn't exactly sure.