VGA is Analog, and DVI-D is Digital only. Although: DVI-I carries both an analog and digital signal, so if you want a non-active (passive) adapter you HAVE to use the DVI-I connector. If you will comment your manufacturer and model, I can tell you (looking at the pictures) if it has a DVI-I connector or DVI-D connector.
The connectors are 90% of the time like the reference (founders edition) card, which has a DVI-D (which is bad for analog).
Alternatively, you can look at pictures or websites online for the difference between DVI-I and DVI-D.
Hope this helps.