Alright, here is an update of sorts. I removed one of the memory sticks at random from out of my disk so I am back to 512 rams. The files that were corrupted on the hard disk still remain corrupted but I believe that may be due to the fact they were on the disk.
I did the test by installing World of Warcraft and patching it(something I couldn't do before) so that the game works now. Now, is there any sort of "valid" test that this did the job and that everything is alright now, and if it is, what am I to do with the other memory stick which might very well be working just fine but doesn't "agree" with the other? Or is that one, which I pulled out, not working and if yes how can I tell in some tests?
Also thanks to everyone for helping in at least moving the issue forward and making me somewhat bring stuff on a normal track.