The 8500 is better than the 9000, hence the price. The 9000 is ATi's response to the GeForce4 MX. Take a look:
8500's features:
Intense graphics realism in 3D gaming environments and workstation applications
Powered by RADEON 8500 GPU for revolutionary performance
3D resolutions up to 2048 x 1536
OpenGL® driver supports fast 3D/2D graphics acceleration
Dual monitor support
Supports Mac® OS 9 and Mac® OS X
Designed and manufactured by ATI
64MB DDR memory offers fast processor speeds and advanced 3D/2D graphics performance
Rapid acceleration of graphics intense OpenGL®, QuickDraw® and RAVE® applications
Your favorite 3D games or workstation applications will run true color 3D graphics with resolutions up to 2048 x 1536 with dynamic realism and stable performance
TRUFORM technology makes characters and objects more rounded and natural
SMARTSHADER technology enables custom vertex and pixel shader programs for complex geometry, texture and lighting effects in real time
SMOOTHVISION, ATI's advanced anti-aliasing feature eliminates distracting visual artifacts for smoother-looking images
CHARISMA ENGINE II supports full Transformation, Clipping and Lighting (T&L) at 62.5 million triangles/second peak processing capability
PIXEL TAPESTRY II, the RADEON 8500 3D rendering engine, powers an incredible 2.4 gigatexels/second for superior fill rates in 32-bit at high resolutions
The RADEON 8500 MAC EDITION supports traditional CRT monitors, flat panel displays and TVs
VIDEO IMMERSION II technology enables integration of industry-leading digital video features, including advanced de-interlacing algorithms for unprecedented video quality
Process full-frame, full screen DVD or MPEG-2 video
And now, the 9000:
Advanced 3D graphics and visual quality for high performance gaming and design applications
Dual monitor support including ADC for Apple® flat panels
Operate two digital flat panels simultaneously at resolutions up to 1920 X 1200
Powered by the RADEON 9000 Pro Graphics Controller
Comprehensive Mac® OS X and OpenGL support
Equipped with 64MB DDR RAM and the RADEON 9000 PRO visual processor.
Advanced processing speeds allow for accelerated 2D/3D graphics performance.
SMARTSHADER technology allows users to experience complex, movie-quality effects for ultra-realism in next-generation 3D games and applications
SMOOTHVISION technology enhances image quality by eliminating jagged edges and bringing out fine texture detail, without compromising performance
ADC connector port
DVI-I connector port
DVI-I to VGA adapter
As you can see, the 8500 has much more to offer than the 9000. The names are quite confusing. It's like AMD calling their 1.4GHz chip the "2100." Go figure.