How do i manually manage my new iphone without erasing everything?

OK, so i got a new iphone 5 for christmas. i already have an ipod touch so through icloud i restored everything to my new phone. then i went on to my computer to add my cds since you cant do that through icloud, and when i tried i couldnt. then when i tried to set it to manual manage it said you can only sync to one computer at a time, and gave me two options: erase and sync or cancel. i understand this happening if it was a new computer and i previously synced my phone to another computer, but for me thats not the case, this is the first computer ive used with my new phone. if syncing were to erase only my pictures, songs and videos i wouldnt mind just deleting everything but it will delete all my apps and app info, and there are things i need. is there anyway i can manually manage my new phone without erasing everything????