Mid 2010 27" iMac problems after installing new iTunes

[SogeKing]

Hi, I was hoping someone might be able to help me with my problem. I installed the new iTunes (10.6) yesterday and my iMac has been almost completely unusable since. iTunes no longer opens up, everything else is running completely slow. I was thinking of restoring from a time machine back up, but my last back up is from October and I can't lose any of my new documents/ and school papers, also I would like to keep my pictures. I have been trying to make a new back up so that I could do a clean install and keep the important files but the time machine software has been "preparing the backup" for hours. I'm at a loss, and any advice or help would. Be appreciated, any more info anyone needs I will try to provide but the Mac has been at a screeching halt all day. Thanks in advance.