Im sick of people debating over which system is the best. I can put this debate to a rest, as far as hardware is concerned, anyway. game quality is another matter...
first, the GameCube
485 MHz
32-bit integer
64-bit floating-point
64KB L1 cache (32KB instruction + 32KB data)
256KB L2 cache
1.94 GFLOPS
CPU external bus
64 bits wide
162 MHz
1.3 gigabytes per second bandwidth
(GPU) ATI Flipper
162 MHz
4 pixel pipelines
1 texel per pixel pipeline
4 texels per clock cycle (4 pixels with 1 texel per pixel)
Maximum of 8 texture layers per rendering pass (done in 8 clock cycles)
650 megapixels per second
Point, Bilinear, Trilinear, Anisotropic Mip-Map Filtering
Perspective-Correct Texture Mapping
Environment Mapping
Subpixel Anti-Aliasing
33 million polygons per second (peak)
6 million to 12 million polygons per second (with effects)
Hidden Surface Removal (HSR) based on early Z-test
Virtual Texture Design
2MB Embedded Frame Buffer
1MB Embedded Texture Cache
10.4 gigabytes per second texture cache read bandwidth
scene texture data stored in 24MB 1T-SRAM main memory
8.6 GFLOPS
The PS2...
Emotion Engine
294.912 MHz
128-bit integer SIMD
128-bit floating-point SIMD
24KB cache
450 Dhrystone 2.1 MIPS
6.2 GFLOPS
Geometry:
66 million polygons per second (peak)
38 million polygons per second (lighting)
36 million polygons per second (fog)
16 million polygons per second (curved surface generation)
(I cant find PPS with effects applied.)
Graphics Synthesizer
147.456 MHz
16 pixel pipelines
2.4 gigapixels per second (no texture)
1.2 gigatexels per second
Point, Bilinear, Trilinear, Anisotropic Mip-Map Filtering
Perspective-Correct Texture Mapping
Bump Mapping
Environment Mapping
32-bit Color (RGBA)
32-bit Z Buffer
150 million particles per second
25 million polygons per second (48-pixel quad with Z, Alpha, and Texture)
And the Xbox...
Intel CPU
Modified Pentium III (Celeron)
733 MHz
32-bit integer
80-bit floating-point
64-bit MMX
128-bit SSE
32KB L1 cache
128KB L2 cache
2.93 GFLOPS (SSE)
NVIDIA XGPU
250 MHz
1.0 gigapixel per second
2.0 gigatexels per second
4.0 billion anti-aliased samples per second
Point, Bilinear, Trilinear, Anisotropic Mip-Map Filtering
Perspective-Correct Texture Mapping
DotProduct3 Bump Mapping (DOT3)
Environment Mapped Bump Mapping (EMBM)
Volumetric Textures (3D Textures)
Z, Stencil, Shadow, and Multisampling buffers
S3TC and DirectX DXT1-DXT5 texture compression
Full-Scene Anti-Aliasing (2x, Quincunx, 4x)
125 million particles per second
60 million polygons per second (with effects)
Triangle Tessellation
Z-buffer compression and Hidden Surface Removal (HSR) based on early Z-test
95 to 116 GFLOPS (estimated)
Max resolution 1920x1080 interlaced
What does all of this techno babble mean? basically, it means that the Xbox is the most powerful system with its 60 million polys per second fully rendered, as opposed to 6 - 12 million for the GC, and tho it doesnt say for PS2, probably around the 18 -24 million range.
Just as a side note, GC is my favorite system cause of SSB:M, and xbox my second cause of Halo 2

Playstation 2 is my least favorite, coming behind the N64, SNES, NES, Genesis, Dreamcast, Jaguar, Atari 2600, Commodore 64... you get my point.