First game on my new computer?

Wondering what people think I should christen my new computer by playing and installing as the first game of it, thinking  either:
Red Faction Guerilla
Dawn of War II
Dawn of War II:Chaos Rising
Mass Effect
The Witcher
Dragon Age Awakening
 
Ideally I would like to play something that can highlight the better graphics card I have on this machine.

Are you familiar with Starcraft 2?

" Are you familiar with Starcraft 2? "

Any recs for the games I currently own though?

Well, if you want to make use of your new graphics card, the real-time cutscenes look like this:
 

Mass Effect definitely. The plot, character development and lore is just amazing. 

Dragon Age: Origins and Awakening is a good choice if you are into, fairly, hardcore RPGs. 

Of those games either Mass Effect or Red Faction would be my pick. Then run off to the store and buy Starcraft 2!

If you weren't able to before, pumping up the graphics in Dawn of War II for the first time is pretty nifty.

Red Faction Guerrilla is a lot of fun. I have spent 600hours in DoW2 + CR(still playing). Mass Effect is awesome. I hate the Witcher. Haven't played DA:A yet...

Personally I would say Mass Effect. If you really want to stress your hardware I'd say Metro 2033 is your best bet.

Dirt 2, not the biggest stress on your computer but has fantastic visuals.

I'd highly recommend you get Steam on your computer. That service is amazing. Also, you can download Alien Swarm and Peggle Extreme for free.
 
Starcraft 2 
The Witcher (Make sure you add every update) 
The Orange Box 
Bad Company 2 
Mass Effect 
Left 4 Dead 2 
 
That should get you started.

Bad Company 2, if you got a DX11 graphics card, this is the game to play