In terms Linux hardware support the best you can get out of the box is with Intel hardware esp the Motherboards by intel itself.
Since you have opted for AMD platform support for CPU and Chipset is good in linux, as long as you use a distro that uses current kernel version
however in terms of driver support for Radeon GPUs (onboard or discrete) under linux is still not upto the mark
There exists two types of drivers for Radeon GPU under linux. First one is OSS Radeon driver maintained by the community and sponsered by AMD (
http://www.x.org/wiki/radeon), second is the catalyst driver which is the proprietary i.e closed source driver developed and maintained by AMD themselves.
Featurewise i have found OSS driver is now good enough for regular usage like web browsing, video playback(not Full 1080p) etc and also all the compiz, Kwin bling :-) . however if you want to do any 3D intensive stuff like blender, gaming etc you will have stick to the Catalyst drivers since 3D support for OSS radeon is a work under progress