As a result of changing PC's over the years and not placing much value in photo organization, I have about 50 DVDs/CDs with photos which are very poorly organized using inconsistent directory structures, and many photos are duplicated yet have different names and might be located in directories with different names. Many of these photo's are on my current hard drive, however, others may not be.
How can I utilize Picasa to copy only those photos on the DVDs which are not currently on my hard drive?