How to save my text messages from my iPhone to my computer?

I just upgraded my iPhone and I'm selling my old 3GS. Before I do this, I want to save all of my text convos. How can I do this for free?

You could screen shot them and email them to yourself, accessing them with your computer. What other format is there for a computer to view text messages?

Use iCloud! Backup your files on iCloud on the 3GS to your cloud, then on your new iPhone upload them from the cloud! They should transfer your text messages.

ITunes is one solution and have you ever tried PC Suite for iPhone?
http://91.pandaapp.com/software/iphone.shtml