Hi, everyone

I want to buy a laptop for ubuntu.
I have check http://www.ubuntu.com/certification/desktop/
It contains brands and models which are compatible with ubuntu. However, a lot of them are out of production, and even they are still in the market, they usually have a better and cheaper new replacement from the company . I think the reason is the product comes out too fast to get into this list.

So. I am still confusing which one I should buy. In this list, lenovo thinkpad series and dell have the most certified product for ubuntu. I also check the forum, it seems that lenovo T series is a good choice. But I don't like the style of T series, and it's expensive.

I want to go to Dell. The list gave me the impression that almost all the product from Dell support ubuntu. I guess even for the new product that isn't in the list, if they have similar components as the ones in the list, they are supposed to works fine , is that true ?

After install Ubuntu, I most concern the following issue: (1) it have sound, I can play music (2) the video card work fine , I can play movie (3)I most concern: I can adjust the brightness by the hot key in the keyboard,

Anybody know which model fulfill my above requirement? how about the dell alienware m14X(Can I adjust the brightness) ? and other similar model?

Sorry for writing too much , I really want a ubuntu running fine on my system. I will be very appreciated if you can give me some suggestion.