I didn't have my own laptop yet, so I had my iPhone synced to my sister's computer. Her computer crashed and lost everything on it, and I just got a PowerBook G4 and want to sync my phone to it. Will I lose all my music and pictures off my phone if I sync to the new computer? Is there a way to sync and not lose everything? Thanks in advance.
From my understanding Apple will only an iPhone to be synched with one computer at a time. I've had similar issues and had to use a program to transfer the music from my iPhone to my computer, then transfer the music from that program to my itunes account. There may be other ways, but that was my experience.
Go to download.com and do a search for "Ipod to computer" or something like that. A bunch of apps will come up where you can move everything off your iPhone to your new computer. So that way you can import all the stuff into your computer iTunes library and you won't lose your stuff. You'd have to find a Mac specific one but I used a couple before for PC. And when you hook your new iPhone up to iTunes, right clock on it and transfer all purchases. So all your apps and music you bought will be transferred to iTunes. Here are the apps I used but like I said you just need to find one for Mac.
There are paid apps that can do both but can't beat free. A quick google search will probably help with finding some other apps too. Try keywords like "transfer ipod files to computer" and you should get a lot of helpful results.
There are utilities that transfer the contents of iOS devices to computers. Let me know if you need a suggestion for one.
Besides what mentioned above, i like to share you a page about iPhone Transfer Backup Reviews, which included transferring iPhone contents to computer/iTunes.
Hopefully this works for all of you like it just worked for me!