Wrong signature from ATMEGA8-16PU after setting fuses with avrdude
Looking at:

http://frank.circleofcurrent.com/fusecalc/fusecalc.php?chip=atmega8&amp;LOW=DF&amp;HIGH=CA&amp;EXTENDED=FF&amp;LOCKBIT=FF

I see that you've turned off all of the CKSEL bits, which seems to select "external clock". Supplying a square wave to XTAL1 on your AVR might work.