itunes/sync help

Just got a mbp and I'm having trouble syncing my iphone. The phone is able to charge through the laptop but it does not appear anywhere within itunes. Not sure if this matters at all but I just added Windows 7 through boot camp. Also, (once again not sure if this matters) I've used an older mbp for a few years and have always synced this iphone through that computer. (I transferred my itunes library using an external hd).

I'm sure this is a very stupid, newb question but I really need help here. Thanks in advance.

Did you de-authorize the other computer and authorize the new one or it will continue to
sync with the one you set it up with been there done that.

how do you de-authorize a computer and can it be done if the computer in question does not exist any more.