So how do I control my computer with voice?

I got to thinking and I have no idea why this isn't built-in top of the pop stuff.

"Windows, open Internet Explorer" "Windows, go to reddit.com" "Windows, play bigbangtheory.avi"

???? I looked around and saw some programs, but they seemed inadequate and mostly designed for disabled people. I see that W7 has something built-in, but not available in my language and probably not that great.

Sooo, where do I download this? Take my money.