Someone else said it in another topic but here it goes...
When restoring, hold down Option when you click the Restore button. It should give you the option to choose what file to restore with. Search for the 2.0 one in the search window and give it a go. I'm doing it right now and keeping my fingers crossed. Otherwise, I'm screwed.
NOTE: This is if you have already downloaded the 2.0 update but it didn't work.
EDIT: IT MAY JUST HAVE WORKED! Download completed, no errors. Auto-restarted the phone and now loaded back onto iTunes trying to access the store. Still waiting.
Ok, so if you've downloaded the 2.0 update but gave you an error when completing it then keeps on giving you more errors when you try to restore it, hold down the "Option" key when you click on "Restore" on the main window. Windows: "Shift" + "Alt" I believe, for Macs it's "Option".