Y2K - the computer problem - was a real deal. Not so much "OMG we're all gonna die!!!!" type of thing, but there was the potential for a lot of computer glitches to occur. Nothing much happened because we realized the potential problems, and the industry corrected the vast majority of vulnerable software.
2012 is a whole different issue. All of these doomsday predictions are crazy talk. Mystical nonsense of times gone by. You can't predict the future. If something ever happens to wipe us all out, I can guarantee you that Nostradamus, the Mayans, nor any other ancient fortune tellers will know about it.
I actually heard recently that they're now saying the Mayans were "off" a bit, which totally ticks me off. I just want the day to come and go so I can FINALLY say "See? I told you." when absolutely nothing happens.