Kingston > Transcend
nVidia has lot of issues with linux/X due to their closed binary drivers. ATI looks like a better deal nowadays atleast for linux.
most of the intel chipset boards work well with linux.
you need to ask graphics designers who actually work on linux. they have much better experience of what to buy. ask people who use blender, etc. everyday.
for hard to find hardware try http://www.primeabgb.com/