The rename trick works only if you do it as root, which means you have to first turn on your root account, and then, as root, fix all the permissions on the renamed folder. That's definitely Genius Bar shit.
I really really really recommend you upgrade your machine and start using Time Machine. You are always going to run into problems if you don't have a backup of 100% of everything that is constantly updated. Time Machine would have been able to roll you back. Alternatively, use Dropbox for your most important files, which works like iDisk but better, and is free and cross platform.