from what I have read about Xgrid, this could be possible.
You need an X-Serve running 10.4 server and your clients also need to be running 10.4

The Xgrid controller, built in to 10.4 server will control all the tasks and will dole out portions of a job to whatever clients are in the cluster. It also collects finished tasks and sends out retries for failures.
All the participating machines need to be connected to an ethernet (faster) network.

Google for Xgrid, lots of hits, or go to the Apple site, www.apple.com/acg/xgrid for more information


P