I think this quote is a rather good one:
“We’ve seen companies significantly improve their brand reputation through a positive online experience; a great Web site can be as impactful as a 20-minute infomercial,” said Dr. Brown, an expert in social psychology and consumer interaction with the Web. “It’s surprising how poorly some venerable brands performed in terms of delivering a positive online customer experience.”
Keynote Study Shows Dell and Amazon Deliver Best Online Customer Experience
New Study First to Examine Online Customer Experience in Computer Hardware Industry