Currently Being ModeratedJan 2, 2013 8:26 PM (in response to high-fives-and-stage-dives)
Is the content on your iphone in your Mac Air laptop? or is it still on your old laptop?
If you sync your iPhone without this it will erase your music from the iPhone and if it is not already prior to syncing in your Mac Air itunes you will have lost it forever.
So either copy your content from the Old computer to the Mac Air
This is how
Or if the only place you have it is your iPhone then try this