notepad is a good program.
You would probably want to learn C++. C might also be usefull.
It might be easier to start of with some more simple programming stuff like java or htmlm though these probably won't help you at all when talking about creating anti-virus or backup programs.
But I'm really just a total noob when it comes to programming, there are many people here with more info about programming so you might want to listen to them instead of listening to me.