AVR-Chat

usually, bypass capacitors are placed at all vcc pins of ic's and are 
layouted as near as posible to filter out voltage ripples...i tried to 
measure the ripples using digital scope and it was around 300mV...but 
i think my scope is not accurate since i get a 300mV ripples even when 
my probe is not connected or connected to ground...my question is, 
What is the tolerable voltage ripples? there is this called embeded 
capacitance where in the VCC plane has embeded capacitance.By using 
this, the .1 uF bypass capacitors are elliminated...Any idea on how to
compare its performance with the one with .1 uF bypass capacitors?
regards

mago