These are the SwitchResX settings that I came up with late last night that work perfectly. Enter them as a custom resolution, and reboot, then select the custom resolution you created.

Pixel Clock – 85.25

Horizontal:
Active – 1366 pixels
Front Porch – 128 pixels
Sync Width – 130 pixels
Back Porch – 174 pixels
Scan Rate – 47.414 kHz

Vertical:
Active – 768 lines
Front Porch – 2 lines
Sync Width – 6 lines
Back Porch – 19 lines
Scan Rate – 59.64 kHz

Positive sync unchecked for Horizontal.
Positive sync checked for Vertical.

A few notes:

• I did these tests on a 1.83GHz MacBook Pro, which has an ATI Radeon x1600. It may be different for machines with different graphics cards. I believe (but could be wrong) that some G4 era machines need pixel dimensions in multiples of 8, so 1366 may not work (you might need 1360, and adjust the porch settings accordingly).
• An HDMI to DVI cable does not carry audio, so you’ll still need to source the audio somehow. I use a Mini-Toslink to Toslink cable connected to my surround receiver. With a few tweaks, it can also output surround sound via Front Row, Quicktime and VLC.
• These settings work on a VX37L. I do not know if it’s any different for a VW37L or an L37. It’s also possible that these settings will work on a VX32L, VW32L or L32, as they’re also 720p displays.
• These settings might work for DisplayConfigX, but since the author isn’t kind enough to let you try the software before purchasing it, there’s no way for me to know for certain.

Update 2/21/08:
Reader Joe chimed in with success on his Vizio GV42L on a PowerMac G5 with a Radeon 9650. He mentioned he had to use 1360 for the horizontal resolution, I assume because the Radeon requires the resolution to be a multiple of 8, as many older ones do. Here’s his settings:

Pixel Clock – 85.25

Horizontal:
Active – 1360 pixels
Front Porch – 128 pixels
Sync Width – 130 pixels
Back Porch – 174 pixels
Scan Rate – 47.573 kHz

Vertical:
Active – 768 lines
Front Porch – 2 lines
Sync Width – 6 lines
Back Porch – 19 lines
Scan Rate – 59.84 kHz

Positive sync checked for Horizontal.
Positive sync unchecked for Vertical.

This leads me to wonder if other Vizio 720p models will work with similar settings.