OK There are a few ways to solve this problem. I started typing directions for the way I would do it but then I realised that it may not be the easiest way to understand. So, after some thought I believe the following might be the easiest to explain:
right click "my computer" and go to proporties. click on the hardware tab and open the device manager. There should be a category called graphics controller or called video devices or something similar to these names. Click the plus symbol (+) next to this category and it should show you all the video devices installed on the machine.
If it shows you two (your geForce 5500 and also your intell onboard video) then you want to just click on the onboard one and click 'uninstall'. This will uninstall the onboard video drivers and should switch the default video output to your graphics card. If only the intell card is shown then report back because that isnt right. After you uninstall the onboard video drivers you should be able to restart and switch the plugs.
Here is what is confeusing your system: you have two video devices installed and the crappier onboard device is the default device. You want to make the 5500 card the default. The above directions shoudl do this. It can also be done in the video settings window however, my concern with trying to tell you to switch it using that window is that it asks you to confirm your selection in under 15 seconds, and you have to change the cable before that 15 seconds is up in order to click 'yes'. If you dont make it in time - it switched back - its a hairy mess. Hopefully this works for you and i'm sorry it is taking you this long to solve this problem as it would literally have taken about 25 seconds had I been there in real life to help you.
