Target an older iOS device

After I blew up my previous MacOSX environment, I went ahead rebuild everything, and reinstalled the XCode. I then found out that I need to regenerate the certificate, request a new one. (Seems like this is Apple's way to make sure that at any given moment only one machine is being used associate with one development account. Things started working after then.

But then I got an error deploying the application to my iPod Touch which runs iOS 3.1.3. No problem, though, since all I need to do is set the "Target OS" back to 3.1.3. I got the hint form this link.