How to move data from ipod touch (apps, music, videos, photos etc...) to a new computer?

I just got a new computer a few days ago and i tried to get my ipod to sync to it. It didnt sync! :( It just said that I am synced with another library and it says that i must erase and sync to begin using this library! But i cant do this! :O I have thousands of songs and hundreds of apps on my ipod and i dont want to get rid of them! Do you know how to solve this problem without downloading something?