Just wanted to share this small piece of information that can help many . If you want to Run your AVR at 8MHz from the internal oscillator you need to disable the CLK/8 Fuse. You can do this by burning new fuse values. This can also be done in you main function as well. Below is a piece of code that will change the pre-scaler to zero.
// set the clock speed to "no pre-scaler" (8MHz with internal osc or
// full external speed)
// set the clock prescaler. First write CLKPCE to enable setting of clock the
// next four instructions.
Hope this will help!