I personally bought my laptop from linuxcertified, which enabled me to verify that all of the devices had linux support and what the necessary drivers were before I replaced the pre-installed system with Gentoo. Of course, considering that I had no intention to run any system that I could get pre-installed, and wouldn't actually want to run something I didn't know how to install, getting a computer with Linux actually already installed, rather than a computer that has identical hardware to one that the vendor would support Linux on, hardly matters to me.