Ohhh Barnicles HELP iPhone 3G

I bought my iphone 3g from my brother who just moved out of the country. He sold it to me when his contract ended with AT&T. I have another provider but my contract is up in October and I am switching to AT&T. I pulled the phone out to show another friend who is considering buying an iphone and now the screen is on connect to itunes I connected it to iTunes and it says to restore it, I tried to restore it but it says there is an error that cannot restore it.
Should I take it to the Genius bar? There is a warranty still on the phone until the end of September.
Any suggestions appreciated
Dell Laptop VISTA