I have the same issue, and I think I have added the 640x480 resolutions to the Nvidia control panel.
Under Display -> Change Resolution -> Resolution (box containing list): under HD, SD I have 1080p, 640x480. Under PC I have 640x480, which were added by Customize and checking all the possible 640x480 options.
However, I still get the small movies. Am I missing something?
from my .ini
Reverse Mouse Buttons=0
Hide InGame GUI=0
Use Small Fonts=0
Keyboard Camera Deceleration=2000.000000
Keyboard Camera Acceleration=500.000000
Keyboard Camera DPS=200.000000
Enable Mouse Teleporting To Buttons=1
Auto Level Up NPCs=0
Reverse Minigame YAxis=0
Disable Vertex Buffer Objects=1
Thanks for any help you might have!
EDIT: Now it seems my lower res games scale and skew to my 1920x1080 native res, and no longer play at their proper aspect ratio with back bars. How do I turn off scaling?