Technology developed

I need to have faith in technology soon.  My computer is older and running out of memory.  I have more than 7,000 pictures saved on my computer and it's time to off load a lot them onto an external hard drive.  This is where my faith must come into play.  My faith that this will work because these photo's are D's entire history!  It's soooo scary.  I know that I could probably purge more than 1/2 of these, but how?  How do you choose 1 photo over another?  

This is where technology and old school compete.  Back when we had film camera's, we were only allowed to take a certain amount of photos.  Film rolls came in 12, 24, and I think 48 pictures - that's it.   When you got them back from the developer, you went through those hard copies and tossed out what you didn't like, but you were limited to the number of photos.  Well, with technology our digital camera's can take as many pictures as a 2, 4 or 8 gig card will hold.  Then we just download those photos onto the computer and the card is empty - start again.  Once those photos are downloaded on to the computer, yes, we can delete, but sometimes we keep those "silly" photos that we'd probably had purged in the past.  We keep the ones where Aunt Sally has her eyes closed because it's a fabulous picture of us, the multiple pictures of our infant baby just laying there because how do you purge pictures of your baby, and the multiple pictures of the flowers in the garden because it was the time where you were playing with your new cameras features.  Keep keep keep.  My edit button is broken, but edit I must and then I must have faith that the pictures will upload correctly to the external hard drive.  Crossing my fingers.