Can't upload sketch to Arduino Uno
The AVR Dude compiler that Arduino uses has some issues with windows 8, but it may be that you installed the device driver incorrectly. If so you should go into the device manager, and click the 'update driver software' on the Arduino Uno. Then browse to find the driver manually and select the 'drivers' folder from where you installed the arduino IDE. If after installing the drivers it still doesn't work, then it is probably an issue with AVR Dude and you should e-mail the Arduino people. Good luck!