Which Alienware exactly is this?

http://cgi.ebay.com/Alienware-Area-...ps=63&clkid=9021428402866733530#ht_3256wt_939

It looks cool and I'd like to get it for my system, but I don't know what system this was intended for. I currently own an area-51 m15x, and I was hoping that this would work on it, but I'm unsure, the touchpad does appear to be drastically different though.

 

That is a limited edition of the Area 51 m15x that came pout together with a few other limited editions. You can actually still get them, you just have to look around on the net a bit.
The picture, of course, only shows the casket, but it was sold as a complete system.

http://www.engadget.com/2006/06/07/alienware-introduces-superman-themed-limited-edition-systems/

 

That's NOT for the m15x so don't buy it because it won't fit on your m15x. It looks like it belongs to the Area-51 m5550 which I used to have (Here's what the original one looked like LINK. The touchpad gives it away.