The primary issue with the ATi chipset is that it is an ATi chipset. The Linux drivers do not perform as ATi had promised, and that is what is causing most of the non-flash performance issues. (Flash is much better, but not perfect, on nVidia.) So while yes, that video card would work well with the LINK board, it would not improve your performance much since it uses the same driver base.
However, the ATi should be able to handle Blu-Ray playback... What drive are you using, and what playback software? It appears that there's only one or two programs available (PowerDVD has the most chatter) for Linux that handle Blu-Ray without questionable legality.
Tested with both the current link software release, but I've also tried ubuntu 9.10 with:
0 10:13:02 tv@tv ~
0 %> dpkg -l |grep fgl
ii fglrx-amdcccle 2:8.660-0ubuntu4 Catalyst Control Center for the ATI graphics accelerator
ii fglrx-kernel-source 2:8.660-0ubuntu4 Kernel module source for the ATI graphics accelerators
ii fglrx-modaliases 2:8.660-0ubuntu4 Identifiers supported by the ATI graphics driver
ii xorg-driver-fglrx 2:8.660-0ubuntu4 Video driver for the ATI graphics accelerators
0 10:13:07 tv@tv ~
As for the source, any mkv encoded blue-ray video. File props attached to this post.
I stumbled across this forum while researching how to set
up a 786g chipset for video playback. A lot of the information
seems to the same for the 780g the link seems to use.
For video playback , you seem to be using the wrong driver.
You don't want to use the fglrx driver except for 3d or using
the XvBA backend, which it does not seem the link is doing.
YOu should switch to the x11-driver-ati, though this does not work right
without also changing the device section of your x11.config to add the line
Option "VideoOverlay" "on"
you may also want
Option "AccelMethod" "EXA"
Another interesting alternative is the broadcom crystal hd card, which also had a joint press
release with adobe about flash supporting it. So maybe an OEM version could be licenced
that used it.