I like to archive my main holiday images on to DVD. I know Picasa has it’s own built in backup tool that will span multiple disks, but it presupposes (I guess) that you (a) will always be using the same program for viewing and re instating your images. I’ve been searching for a simple ideally free application that does the job. I’m pleased to report that  http://cdburnerxp.se/en/home does the job very well. Just add your files to the target list. It will compute how many CD’s or DVD’s you need and manage the process. Have fun.