I have OS10.5 and an iPhone5 how do I get my apps, photos and music?

I have an Intel iMac core duo with OS10.5.8 with iTunes 10.6.1. I have a 3GS which I recently upgraded to an iPhone5. I sync my 3GS and headed to the store to pick up my new phone. The AT&T guy hands me instructions which says I need to update my 3GS (iOS5) device before syncing the new iPhone5 (iOS6). iTunes would not let me update beyond 10.6.1. Apple, true to its word, I rec'd iOS update on Sep. 21st. So I turned on wifi and update my 3GS to iOS6. OK now my itunes does not recognize either phone because they are both iOS6. I never thought for a moment iTunes would not recognize my devices. Now I'm perplexed. I'm worried the answer is going to cost me more money.

I do have a wintel XP at my disposal which just downloaded iTunes7 onto, but of course, I have no previous backup stored. I can't figure out how to get my apps, photos and music onto my new iPhone. so, when I try to restore, it displays message that if I want to do this it will erase everything on my 3GS. Funny how itunes 7 is compatible with XP but not Leopard, but that is another discussion.