Question on restoring from a 4s to an old 3gs

Hi,

I just sold my iPhone 4s in anticipation of the 5, and want to restore my data to my 3gs.

However, I'm running into some difficult.

This was my plan:
1. Backup old iPhone 4s before selling (done)
2. Wipe iPhone 4s
3. Get SIM for 3gs
4. Restore the 3gs using the 4s's backup file

HOWEVER, now that I am trying to restore, I'm running into these two problems:

1. The "restore from backup" option is not present when I select the properties of my phone in iTunes where it would normally be

Why would this be?

2. I thought it might be missing because the 3gs is running 4.3.3, while the 4s was running 5.1.1. However, when prompted to update my 3gs to 5.1.1, it warns that it will sync all of my contacts/etc with iCloud. This obviously seems dangerous because my current iCloud is up to date, and I don't want my old contacts from the 3gs overwriting the current ones.

Any tips?

 

Solved - I just erased contents, setup as new, installed iOS 5.1.1, then restored.

My guess is that if the phone is on 4.x it won't let you restore from a 5.x backup until you update the OS.