Not sure which exact build model (sales order number) and screen size spec of your MacBook,
but if you have a MacBook Pro (mid-2010) there were a few display adapter cables in common.
For Display has 1 - Mini DisplayPort uses (VGA, DVI, or dual-link DVI with adapter)
The Dual-Link DVI with Adapter would be the costly one. A search online brought up several
examples of the Apple part, here is one of those (at amazon) for under $100; there are others.
http://www.amazon.com/Apple-MB571Z-DisplayPort-Dual-Link-Adapter/dp/B001IF252C
You may need to double-check the specification of your computer model because there may
be more than one kind of dual-link adapter, and note "Mini DisplayPort" is the specification.
And depending on the kind or type of display (or projector, etc) you have, the adapter may vary
since you did not specify, some displays can be used with the less costly DVI/HDMI or VGA.
In any event...
Good luck & happy computing! 🙂