The X300SE is based on the RV370 processor from ATi. The RV370 architecture utilises 4 pixel pipelines which is no real progress from the older generation 9200SE, as well as 2 vertex units, one more than the 9200SE.

This RV370 chipset is of course, PCI-Express-native and just like all X300 and X600 based cards, there are no plans for AGP versions of the card.

These are the specs as reported by ATITool:

As you can see, the memory bus is only 64-bits wide. Along with the really slow 5ns memories, this is going to hold back the card's performance.

SmartShader™ 2.0
-SmartShader™ defines the level of realism in latest 2D/3D games and applications
-Complete hardware-accelerated Microsoft® DirectX® 9.0 programmable vertex and pixel shader support
-Full hardware support for OpenGL®

SmoothVision™ 2.1
-SmoothVision™ improves image quality by smoothing jagged edges, improving blurriness and refining background details during on-screen motion and at lower resolutions.
-SmoothVision™ settings are user configurable in ATI Catalyst™ Control Panel:
2x/4x/6x Anti-Aliasing modes
-Sparse multi-sample algorithm with gamma correction, programmable sample patterns, and centroid sampling
-Lossless Color Compression (up to6:1)at all resolutions
-Temporal Anti-Aliasing
-2x/4x/8x/16x Anisotropic Filtering modes
-Up to 128-tap texture filtering
-Adaptive algorithm with bilinear (performance) and trilinear (quality) options

HYPER Z™ III
-HyperZ™ ensures optimal hardware performance by discarding irrelevant object data that is not visible to end-user on their display.
-Leverages key features from ATI’s third generation HyperZ™ III technology that conserves video memory bandwidth for improved performance in demanding 2D/3D games and applications.
-Lossless Z-Buffer Compression (up to 48:1)
-Fast Z-Buffer Clear
Z Cache optimized for real-time shadow rendering

VideoShader™
-Seamless integration of pixel shaders with video in real time
-FullStream™ video de-blocking technology for Real, DivX, and WMV9 formats
-VideoSoap™ noise removal filtering for captured video
-MPEG1/2/4 decode and encode acceleration
-DXVA Support
-Hardware Motion Compensation, iDCT, DCT and color space conversion
-All-format DTV/HDTV decoding
-YPrPb component output for direct drive of HDTV displays†
-Adaptive Per-Pixel De-Interlacing and Frame Rate Conversion (temporal filtering)

Additional Features
-Dual integrated display controllers
-Dual integrated 10 bit per channel 400 MHz DACs
-Integrated 165 MHz TMDS transmitter (DVI 1.0 compliant / HDMI interoperable and HDCP ready)
-Integrated TV Output support up to 1024x768 resolution
-Windows® Logo Program compliant
-ATI Catalyst™ Software Suite