backing up iPad to a different computer
Question: I have a full iPad, and want to back it up to a new (to it) laptop.
Details: My macbook pro died (water spill). My time machine is out of date--it went out of sync four months ago, and I hadn't gotten around to setting up a new one. I'm back using an old macbook running 10.6.8, and I don't yet have the hard drive from the macbook pro. In sum: I don't have access to my old iTunes library.
My iPad (#1, up to date) is almost full, and I want to back up all its contents (apps, photos, data/documents) to iTunes. But the only option I'm getting is to erase the iPad. Help!--thanks.
iPad, iOS 5.1