How to get music from old computer to new iphone 5?

My old computer can't use iTunes 7, it won't install, it's too old. But my new iphone 5 needs iTunes 7 to sync. How do I solve this problem and get my music onto my phone?

Added (1). But iTunes 11 won't install on my computer…

You Need Itunes 11+ I don't know where you Got 7From
Apple.com/itunes