On big CRT monitors the low 640x480 resolution of Freespace 1 looks ugly. You see black scanlines all over the screen. But for owners of nVidia cards on Windows XP, there is a solution named double-scan:

1. Download and install NVTweak from http://nvtweak.laptopvideo2go.com/
2. Run NVTweak and change "Default Control Panel" to "Classic"
3. Right-click on your desktop an select "NVIDIA Display". From the sub-menu select your monitor. The GeForce classic control panel appears
4. Click on the "Additional Properties..." button.
5. From the pane on the left side of the control panel select "nView Display Settings"
6. Click on the "Device Settings" button, a popup menu appears, select "Device Adjustments..." there.
7. In the "Device Adjustments" window select the "Display Mode Timing" tab.
8. Enable the option "[X] Enable doublescan for lower resolution modes"
9. Acknowledge all dialog boxes with "OK" and change "Default Control Panel" in NVTweak back to "New" to get back the regular NVIDIA Control Panel.

The nVidia Driver now uses a monitor resolution of 640x960 for Freespace 1 by doubling every scanline. Of course, the game resolution remains at 640x480, but the black lines are gone. The image is much brighter now.

Edit: Alternatively this can be archived by setting the registry key

HKLM\SYSTEM\CurrentControlSet\Control\Video\{GUID}\0000\MonitorTiming

of type REG_BINARY from 00 00 00 00 to 80 00 00 00