OneCare does not backup programs. In fact, no backup of programs will help move them to Vista - if you perform an XP to Vista upgrade, programs that are compatible with Vista will still work. If you format the PC and clean install Vista, you will need to install the programs, including OneCare before restoring your OneCare backup, which is data only.
Personally, if it were me, I would copy the files that are most important to me, and that I would not want to lose, to DVD, CD, external disk or a Network Share manually using Windows Explorer as a fall-back. That way you have the OneCare data backup and a manual backup for safety.
If you are performing an upgrade install of Vista, I recommend uninstalling OneCare before upgrading and reinstalling and activating with your subscription LiveID after the upgrade has completed. Open OneCare and click Help/About... to see your subscription LiveID before uninstalling - you'll need that to activate.
-steve
