Transfer songs from iPhone to iTunes?

I need to transfer all my songs (855 of them) from my iPhone 3g to iTunes using windows. The only options I can find are transfer purchased, or sync. Transfer purchased only transfers 110 of my songs; sync warns me that everything will be removed from my iphone and replaced with what is in my library on iTunes. I havent got any music in my library, so this means Im gonna loose like 700 songs doesn't it? Is there a way of transferring all my music over at all? I'd even be happy with just transferring it to the computer. I just need it off my phone, but somewhere I can still listen to it.

Thanks in advance for your help.