I think I fried it

I was doing some testing with a shiftbrite and a shiftbar and I think I may have inadvertently put 12vdc onto the 5vdc output of the arduino. Now it won't upload sketches and I am pretty sure I fried the ATmega328. I can get a replacement IC no problem but I am concerned if I may have damaged any other components. Should I attempt a new chip or should I just count the board as lost and get a new one?

Time for a loop-back test... http://arduino.cc/forum/index.php/topic,66477.msg488403.html#msg488403