Maybe it's related the brand perception?
Anyway I think that newer apple computers seem to be really a pain under
GNU/Linux, for instance according to the reverse engineering needed and done
by people like Mathew Garret, so better avoid them like the plague.
In the other hand there are companies like ThinkPenguin that sell laptops
that work well with free software distributions like trisquel...
About gaming, many free software games do require 3d, but not all requires
that powerfull graphic cards: some games are playable on really low end
hardware, so a more powerfull system like think penguin's will probably be OK
for some games:
for instance on way older systems such as core 2 duo + intel graphics cards I
can run games such as supertuxkart, and maybe games like Xonotic and the
tremulous successor work, I should check.
I don't think that there are a lot of free software games that require a that
powerful graphic card
And there are also other similar companies that sell laptops with Nvidia
graphic cards...
Personally I bought my laptop(core i7, used for compiling) some years ago and
I've now issues because I didn't bought it from free software friendly
companies:
-> suspend to ram don't work
-> sometimes it fails to boot, I've to power it off and restart the boot from
scratch
-> no 3D acceleration(ATI)
Apart that Wifi works since it has an ath9k(hopefully...)
I've also an x60 with coreboot...and 3d accelration(however I need to buy an
internal wifi card for it),because I fear that having 2 wifi cards makes the
battery life worse.
Denis.