Kids Invest and Develop Savings Act of 2007 - Amends the Internal Revenue Code to: (1) increase the allowable amount of the tax credit for retirement savings; (2) expand eligibility for such credit to taxpayers with adjusted gross incomes up to $95,000 ($150,000 for joint returns); (3) establish tax-exempt Roth individual retirement accounts (IRAs) for individuals under the age of 25; and (4) allow a tax credit for contributions to such IRAs.