On the morning of April 12, 2006, Phoronix had delivered the world's first look at the Radeon X1000 series running under GNU/Linux. That day ATI Technologies had finally delivered Radeon X1000 product support for their fglrx display drivers. This support had come six months after the launch of the Radeon X1k series back in October of 2005. With the Windows Catalyst drivers having had the support for months this lack of support had caused a great deal of controversy in the GNU/Linux community. This support was also in sharp contrast to NVIDIA's same-day GNU/Linux support when the GeForce 7800GTX 256MB was released. To make a long story short, the driver support was finally there but the performance continued to be below everybody's expectations. In our ATI Radeon X1800 Linux Preview we had seen the X1800XL 256MB barely possess any advantages over the ATI X800XL, and in many of the benchmarks the X800XL had even beat out the newer card.
http://www.phoronix.com/vr.php?view=7552

Digg: http://digg.com/linux_unix/ATI_X1000_fglrx_Q4_06_Update