Arduino Mega on Vista 64

When I first plugged it in no message came up saying "found new software" and I couldn't follow through with the setup as shown on the website.

I downloaded all the drivers and installed them in to com 3. Then I tried to start my Arduino program and it would make my screen flash black 2-3 times and then nothing...

I got it working on my old XP-computer. But this vista doesn't seem to allow me to follow as shown on the website.

Any one able to help me? Thanks!!!