Transferring all contents from Ipod to PC

Hello,

I have an iPod touch 3rd gen. I want to know how to copy all of the contents (songs/applications) to the iTunes on my new computer? My problem is I don't have back-up of the stuff I have in my iPod. And most of the applications and songs are not purchased from iTunes. I haven't tried the "transfer purchases" in iTunes yet because I've read somewhere that it only transfers purchased songs and applications from iTunes. Hope you could help me. Thanks!