Read this please: http://windows.microsoft.com/en-us/windows/move-windows-between-multiple-monitors#1TC=windows-7
That's a nice picture http://www.diffen.com/difference/DVI_vs_VGA from Uncle fuzzy
All two of them, can handle resolutions up to 1920x1080 and above.
On papers DVI sends digital and may or not sends anolog signals as well. VGA only anolog.
In real life, you should have a very sensitive TV, and a very clean output signal from your GPU to see any differences versus the VGA cable.
So don't bother with that.
Ahem,...and DVI sends only video signals compared to HDMI that handles audio signals as well. !!!!!!
SIMPLE LIKE THAT !!!!!!