Even though the XBox hardware is better(on paper) I would still prefer to use PS2 as a full computer.
I prefer Sony over Microsoft, it has firewire, 2 USBs and Sony fully support and produce a Linux 'kit' for PS2. This 'kit' includes documentation about the PS2 hardware allowing programmers work directly with the hardware.
Basically this turns the PS2 into a dev system!
Also I keep hearing that the hardware is similiar to that of the Amiga in that it also uses multiple CPUs to allow tha hardware to multitask.