Connecting Apple monitor to Dell latitude E6540
Stepping down from DisplayPort to DVI or VGA is a relatively simple &amp; cheap task.

Unfortunately, going the other way is not so simple... &amp; certainly not so cheap.

I've managed to find these 2 examples of DVI - > DisplayPort adapters, though for the prices you could just about buy a new monitor instead.

I would also be very, very certain that the Apple monitor is, in fact DisplayPort &amp; not Thunderbolt. The connectors look the same &amp; you didn't specify the model in your question.

http://www.startech.com/uk/AV/Converters/Video/DVI-to-DisplayPort-Adapter-with-Audio~DVI2DPA

http://www.amazon.com/AT-DP400-Displayport-Converter-Designed-Convert/dp/B003CWEXWO