Amends the Internal Revenue Code to: (1) extend the tax credit for first-time homebuyers through 2009; (2) expand such credit to include all purchasers of a principal residence; (3) waive the repayment requirement for a residence purchased after 2008 unless such residence is sold or vacated within 36 months of purchase; and (4) require a minimum 5% downpayment on home purchases to qualify for such credit.