Linux learning curve ain't easy for noobs. So, I would say stay with windows. If you can update your OS to windows 7. It is way faster and snappy than vista. Use firefox for all internet browsing with Noscript and addblock installed. You don't really have to use NoScript but definitely use adblock.  IE9 RC build is pretty decent browser but I won't recommend it because of no adblock support. Lastly, use Microsoft Security Essentials as your antivirus program. It is awesome, developed by Microsoft and FREE. Don't install everything that pops at you. Just use your head and you will be fine.