Considering that these are the tools I have to work with: a cd rom drive, a 100 meg zip, and floppies (ha ha!), how can I back up my data files, then on a regular basis, back up only the ones that have changed, or new data files?
Depends on how much you download or add to files. I would do a CD back up at least monthly. and use the zip to temporarily secure data that has been added since the last back up.