Peanut Butter Bars

2 1/2 cups graham cracker crumbs
1 cup peanut butter
1 cup butter, melted
2 cups semisweet chocolate chips
2 3/4 cups confectioners' sugar

In a medium bowl, stir together graham cracker crumbs, confectioners' sugar, peanut butter and melted butter. Press firmly into the bottom of a 9x13 inch pan. Melt chocolate chips over a double boiler or in the microwave, stirring occasionally. Spread melted chocolate over the crumb crust. Chill for about 5 minutes, then cut into bars before the chocolate is completely set, then chill until ready to serve.