If you don't have the curiosity and intelligence to get Windows running smoothlyI do. Everytime I format my harddrives I customize the settings (show hidden files, show file extensions, old start menu system etc.), get the latest drivers, updates, antivirus etc.
As long as you don't run random exes you get from porn sites and other such stupid stuff you'll be fine.I once formated my HDD, reinstalled XP and installed all the latest updates, and 30 minutes later I had shortcuts to porn sites on my desktop.
2. Viruses. Protect yourself better.I haven't had any viruses in the past 2 years.