So you have the files on your PC still (or your memory card from the camera?) If so, there is no need to download them from PB as you still have the originals.
If you dont have the originals (and from read the reply it seesm they arent to hand), you will have to open each photo on PB and then download it - but again honestly it will be quicker to re-assemble the original files and store them on your PC for safe keeping. When you have them all, create a DVD of them - hell, create a few as back up as these are family photos.