The Lenovo Thinkpad I have at the office has a DisplayPort output. Not DVI, HDMI, not mini-DisplayPort. Nothing in the office has a DisplayPort input: the monitors take DVI, the big screen takes HDMI, and all the Mac guys have their little white dongles for mini-whatever-mac-people-use.
(Yes, there are other DisplayPort-to-DVI questions, but they seem centered on hooking up 3rd output from a single video card. I'm just trying to get one digital video signal out of my laptop.)
Monoprice sells several DisplayPort-to-DVI cables and adapters that look mechanically correct, but they come with this scary-sounding warning:
This is a passive adapter. While DisplayPort connectors are capable of passing a DVI signal, DisplayPort and DVI signals are basically different and not compatible with each other. This adapter does not actively convert a DisplayPort signal into a DVI signal. In order for this adapter to function properly, you must have a DisplayPort source device capable of producing and passing out a DVI signal through the DisplayPort jack.
How do I know if my Thinkpad is something that's "capable of producing and passing out a DVI signal through the DisplayPort jack"?