Recently i came to know about this article.... very interesting...
How Changing a Button Increased a Site's Annual Revenues by $300 Million
It's hard to imagine a form that could be simpler: two fields, two buttons, and one link. Yet, it turns out this form was preventing customers from purchasing products from a major e-commerce site, to the tune of $300,000,000 a year. What was even worse: the designers of the site had no clue there was even a problem.
...
The $300,000,000 Fix
The designers fixed the problem simply. They took away the Register button. In its place, they put a Continue button with a simple message: "You do not need to create an account to make purchases on our site. Simply click Continue to proceed to checkout. To make your future purchases even faster, you can create an account during checkout."