I have a old machine with a Nvidia 6600ish video card.

I would like to use a TV for a second monitor. When I pick the dual
display, the lowest resolution choice is 800x600.

When I boot the machine, the TV will display the Windows start up
screen. After the machine boots, the TV displays....unusable signal.

I assume the TV can only display 640x480. Can I set XP to a lower
resolution.

Even when I use Nvidia's TV wizard, the min resolution is 800x600.