DO NOT BUY ATI/AMD…
Everytime someone ask for a graphics card advice, and I tell “don’t buy ATI, buy Nvidia“, I have at least three people popping up “but my card works fine, ergo ATI is definitely OK on Linux” posts. Let’s stop falling into argument from evidence fallacy trap and make sure newbies or anyone looking for an advice get the most stable system possible.
Intel works best on Linux, but their onboard cards have limited capability. Still, if you don’t plan to do 3d modelling; then they are more than enough.
Then comes Nvidia. Their drivers are proprietary, but to my knowledge for the last 5 years they always cared enough to put some nice working driver out there and they always released updates. Only a couple of their mobile system cards caused problems.
Then comes the ATI lottery. You may get something works OK, or something that will make you cry.
Support firms who gives a shit about Linux.