Hi there,
I have a Dell Optiplex 745. When I turn on the computer I get this message:

Attention: unsupported video configuration detected action is required
This computer has an add-in graphics card, but the monitor cable is plugged into the integrated video connector.
To attach the monitor cable to the add-in graphics card:
1 shut down the computer
2 Plug the monitor cable into the add-in graphics card connector this may require a video adapter or video adapter cable (provided with system)
3 turn on the computer

I can't see anywhere else to plug the cable in other than the blue one at the back. Do I need to buy some  sort of adapter cable? Someone told me I need a DVI to VGA cable, is this right, or is there an alternative?