you will need the crystal for normal operation unless you set the atmega fuses to work with internal oscillator
I remember reading somewhere, also, that you need to set fuses differently if you are using an external crystal vs an external resonator, so you may want to check into that as well...
Please enter a valid email to subscribe
We need to confirm your email address.
To complete the subscription, please click the link in the
email we just sent you.
Thank you for subscribing!
via Egeo 16