Graphics resolution:

XBOX: 1920x1080

PS2: 640x480

Processing power:

XBOX: Pentium III 733MHz, 233MHz nVidea graphics processor, DirectX8.

PS2: 294,912MHz

Pheripherals:

XBOX: Standard: 4 controllers, 8GB HDD, 10/100 ethernetadapter, Hardware supported Dolby Digital 5.1 (256 channels) High Definition Television-support for games +DVD,

PS2: Standard: two controllers, DVD (Dolby Digital 5.1 and DTS) (48 channels), two USB-ports (12MB/s), IEEE1394 (iLink)-port (400MB/s).
Optional: Online gaming: HDD+Nic; Linux Kit: 40GB HDD, 10 Base-T/100 Base-TX Ethernet card, USB keyboard, mouse, and VGA AV-connection.

My opinion: The XBox beats the PS2 if we're talking about prestations/quality, no doubt about it. PS2 though is much cheaper, and there are more games available...