Long story but here is the short version:

Had a 3GS with bad hardware. Was on 3.0.1. Had to backup fairly frequently because hw issue was putting phone into recovery mode and would have to restore frequently. Before I could get to apple store to replace...phone went into restore AFTER Apple was no longer allowing 3.0 restores . So I had to upgrade to 3.1 on phone . Did a FULL backup (3.1) right before I went to Apple Store. Got new 3GS. New 3GS has 3.0 FW . Get home plug it iTunes asks if I want to restore from backup. Select from latest backup (the one I did on 3.1 FW) iTunes says "Can't restore from this back up the software on iPhone is too old. Set up as new Phone to continue" . So that is what I did. Setup as new phone on 3.0 FW. Now when I try to restore from b/u...my latest 3.1 backup is not in the list .

Any ideas on how I can get the 3.1 backup to restore my phone or is the backup structure for 3.1 so fundamentally different that I am SOL?

Otherwise my most recent 3.0x b/u is about 3 wks old and missing a lot of info (it was a busy 3 wks) and I don't want to lose it if I don't have to.

TIA,
Brett