Actually I'm trying this first instead, I've created an ISO of the PS2 Reality Media Player 1.50 CD which I'm going to ftp to my HD.
Crossover cable to the PC, install ps2vfs on the PC, set up IPs in the same subnet and I should be right to stream DiVX from my laptop to the PS2.
See 'networking the player' at
http://www.ps2reality.net/users/opeh/150/main.htm
Fingers crossed.