Getting to orbit means more than just blasting off straight up to reach a certain altitude, you'll just fall back to Earth.

Let sir Isaac Newton show you why. (don't worry, you'll have fun)

Newton was familiar with Galileo's work on projectiles, and suggested that the moon's orbit could be understood as a natural extension of that theory. He imagined a gun shooting a projectile horizontally from a very high mountain, and supposed that successive shots drove the projectile faster and faster.

The parabolic paths become flatter and flatter as the cannon is fired faster. He imagined that the mountain was so high that air resistance could be ignored, and the gun was sufficiently powerful.

Eventually the point of landing is so far away that the curvature of the earth must be taken into account in finding where it lands. In fact if the curvature of the cannon's path matched that of the Earth the ball returned to hit the artilleryman on the back of his head.

On this site you will find a Java applet that does just that.

(screenshot)

Although the ISS travels at a speed of 7.7 km per second it is in one of the lowest orbits possible - an approximate 390 km above our heads

References:

http://www.waowen.screaming.net/revision/force&motion/ncanon.htm

http://www.esa.int/esaHS/ESA0I6KE43D_iss_0.html