According to the [on-topic help article][1] you shouldn't ask such a question:

> **Questions that you should avoid:**
> 
>  - Shopping or Hardware Recommendations

Whenever a user asks a question like this I usually mark it as a duplicate of [this question on compatibility][1] or [this question on laptops and certification][2] and let them know that there is really no definitive answer to their question other than "Try it and see."

There should probably be a link to the [Certified Hardware][4] page in the help article though.

[1]: http://askubuntu.com/help/on-topic
[2]: http://askubuntu.com/questions/185952/where-can-i-find-information-about-ubuntu-compatible-or-certified-hardware-pc-mo
[3]: http://askubuntu.com/questions/509512/what-laptops-are-guranteed-to-work-for-ubuntu-is-there-such-thing-as-an-ubuntu
[4]: http://www.ubuntu.com/certification/