Mini-Display port to DVI-D Cable

Ok so I have been doing some research on dual monitors lately and I have found out that the new MBP doesnt allow you to run dual lcds with their display port cables (unless i buy a matrox adapter which is like 200 bucks and it doesnt even create true dual display). I find this incredibly frustrating for video editing but now what I have decided to try is just using my MBP display as the secondary monitor. Now I assume I will be given the ability to do at least this. I was just hoping to verify this works before I go and drop the money on the adapter at the mac store. Anyone running this setup right now? And if so does it work well?

cheers

So you're asking whether you can use an external monitor as the primary display and the Macbook's monitor as the secondary display?

yes sorry i guess i wasnt too clear with that. i just want to make sure i can do that before picking up the dvi-d adapter. I want to make my 20" widescreen lcd the primary and make my laptop the secondary. i mean i assume you can since thats gotta be the reason for most people to do it, but then one would also think that you should be able to run two external displays...but apparently thats out.