kengr

Antivirus programs today usually have what's often called "on-access" scans, which means that when you try to read an infectible file, the antivirus checks to see if it's been infected. Because of this, you want your antivirus to be updating as close to continuously as possible - most of the major players in the antivirus market put out data file updates at least daily, occasionally multiple updates in a day, and the default setting is for the program to check for a new update once per day. Many programs also default to doing a full system scan daily, and if you leave the computer on all the time, like I do, you can set that to happen when you're asleep. Daily full-scans actually happen in the background, so that you can continue to use the computer, at a small to moderate cost in performance.

Note that some install media - especially for games - may not be copyable, or may appear to copy, but the copies will fail to work.

If you have the media to spare, I recommend no less than three rotating media sets for backups. Consider using an image-backup program, like Norton Ghost or Acronis TruImage, so that when/if you have to restore from the backup, you won't have to actually sit there and reinstall software and re-enter keys and (in some cases) call the software publisher to explain that your hard disk went blooey and you need their permission to reinstall because you used up all of the previous allocated installs.