iPhone Sync to New iTunes?

[Redneck]

Sorry if my questions are stupid. I'm still not yet very used to Apple.

I'm going to retire my Vista PC and I'm going to replace it with a brand new iMac. However I don't want to loose all the data (images, music, apps etc) I already have on my iPhone.
When I start iTunes on the new iMac and try to sync it with the phone, it gives me the warning "Are you sure you want to sync music/pictures/apps? All existing music/pictures/apps and their data on the iPhone “Redneck’s iPhone” will be replaced with apps from this iTunes library."

So how do I get the stuff I already have on the iPhone into the new iTunes on the Mac?

[revjvegas]

DO NOT SYNC until you've backed it up off the old and moved it the the new.

Here's one how to: iTunes: How to move your music to a new computer

[groovyone]

I take my USB external full of MP3s and move it whereever I please. iTunes, pssht. That really is my biggest Apple peave.

I am sure my sister will ask me the same qeustion soon though. Thanks for the link.

[Redneck]

Thanks, John. That helped.