While passively scanning through sites offering used Macs, I've found that many sellers (especially those on eBay and craigslist) will, to make their offer look more attractive, include Adobe Creative Suite and, even more often, Microsoft Office. However, in almost every case, these applications are installed on the computer, but a disk for them isn't provided. My question is: suppose I buy one of these computers. Is there any way to retain these programs when I decide to reinstall OS X? I know there's an 'upgrade' form of installation that will keep some of the old data - will that do the trick? Also, what does the lack of installation disks say about the legality of the programs?