My iPhone won't sync to the new computer i got?

Hi guys so i got a new mac and before i had a PC.
obviously my iphone was synced to my old computer
when i connected my iphone to my new computer to sync music and videos, it keeps saying i need extra space on my iphone even though it has like 8GBs left

Make sure you untick sync photos and music

as it may be trying to load all your songs and pics on mac to IPhone and it can't handle it.

Click on phone in iTunes and untick the sync photo's or music see if it syncs.

you may have too much for phone to handle from your computer.

or
download

http://www.macroplant.com/iexplorer/

and get all your stuff onto your new mac then wipe and re-sync

With the ipod you have to choose windows or mac. It can't sync to both. Perhaps that's the case with your iphone. You'll have to format it for mac instead of pc. This will erase everything you've downloaded like apps and music etc.