How do I sync an iPhone with iTunes when it's already sync'd with another?

Question

My old mac died - hard drive went, so I'm starting a fresh now and I've tried to sync my iPhone with the new iTunes but because it is still sync'd to the old one it wants to delete everything off the phone. Is there anyway I can sync without losing everything?
Thanks,
Andy

Answer 1

In regards to iTunes content, an iPhone can be synced with an iTunes library on one computer only. When syncing iTunes content with an iTunes library on another computer, all iTunes content on the iPhone that was transferred to the iPhone from another computer will be erased first. The same applies to photos transferred from your computer to your iPhone.
Contact info, calendar events, and bookmarks can be synced with the supported applications on multiple computers.
If you don't have a backup for your old Mac that includes your iTunes library, iTunes includes an option to transfer iTunes content that was purchased from the iTunes store from an iPod or iPhone, but this is for iTunes content that was purchased from the iTunes store only.
First you need to authorize the Mac you will be syncing your iPhone with - with your iTunes account with iTunes if you haven't already done so.
With your iPhone connected and without syncing, at the iTunes menu bar go to File and select Transfer Purchases From - the name of your iPhone.
If you will be syncing contact info and calendar events with the Address Book and iCal on the Mac you will now be syncing your iPhone with and both applications haven't been used and are void of any data, enter one contact in the Address Book and one calendar events in iCal before syncing this data. Makes these up if needed, which can be deleted later. This will provide a merge prompt when syncing this data, which you want to select.