Hi 1Mac, welcome to the PCHF.
We prefer to stay off MSN with advice, so everyone can see what is going on - and time zone differences are too hard to figure out.
DVI/VGA adapters won't make a difference....it will only make a difference if you have a DVI cable...and even then it's normally not noticable to the human eye.
In regards to the card not working when you plug it in...have you been plugged the extra power into the back of the card (inside the case) and is your power supply big enough to run it?
To find out if you have enough power - goto
PSU Calculator in my signiture and put in all your computer details, it will tell you how much you need...ad 30% onto the figure, and that's how much you want.
EDIT: In regards to disabling the on board video card - this won't make "much" difference....infact, unless you can disable it in the BIOS - it won't make any difference at all.