How to transfer the contents of my iphone to itunes on a new computer?

I got a new laptop (PC) and I want to transfer everything on my iphone (music, pictures etc.) to itunes on this computer. But if I sync it it says it will delete all the data.

SynciOS is a FREE program that claims to be able to transfer data between PC, iPad, iPod, and iPhone, and vice versa, my friend.