Ok...THIS WORKS AND IT"S REALLY, REALLY SIMPLE!! No need to go to risky operations or fiddle too much under the hood, as suggested by some.
Note, this only works in this order...and if you have a recent Time Machine backup.
1. Backup your Itunes folder (I had no problems with this, but always better safe than sorry!).
2. Downlaod Itunes 10.7 from here: http://appldnld.apple.com/iTunes10/041-7195.20120912.d3uzQ/iTunes10.7.dmg . Don't open it, just leave it in your downlaods folder.
2. Enter Time Machine. Go to your last backup and click on the 'Applications' folder. Find Itunes. Click on restore. Enter your admistrator password, if neccessary. This won't replace it but for some reason, it allows you to install 10.7.
3. Install Itunes 10.7
4. When you try and open it, Itunes will say it can't acsess your libabry becase "Itunes Libary.itl was created by a newer version of Itunes". Quit Itunes.
5. Go back into Time Machine and go into, not your last backup, but the one before that (i.e. two back from today). Go into Your name / Music / Itunes. Select "Itunes Libary.itl". Click on restore.
...That's ot!
HAPPYY DAAAYS...no more ITUNES 11!!
Without a doubt the worst update Apple have ever put out, please Apple....no more like this!!
Ben