Time Machine backs up everything, every time. already threads but no answer.

upgraded to Leopard a couple of weeks ago, tried to get Time Machine working with my external hard drive, and was happy initially with the results.

But on further inspection, time machine is backing up my entire computer every hour. How can i stop this to only back up what has changed.


Also, i want to make my external Hard Drive the main disc where everything goes, not just use it as a back up. How can i do this? I tried to do this with my iTunes library but now if i download a new track it immediately saves onto my computer hard drive.
Also, the songs i already had on my laptop are backed up onto my time machine, but they aren't in the same folder as the other stuff which i uploaded after moving the iTunes folder onto my Hard drive, they are still with the backed up stuff.

Any help would be much appreciated, I am aware other people had the same problem, btu i searched and could not find an answer....
Thanks