I don't know how to use XGrid, but you can install XGrid on all available computers, have one host computer, and it will take all the other computers processing power. Then, you install F@H on the host and use it maybe?
I dont know but it needs to be exploited if at all possible. I only have my one G5 as of now so there's no point in me trying to test anything. I think the client app as to be written to take advantage of xgrid. I know they have discussed it at Pandegroup but thats all they will come clean with. (for now)
As I told him I would be willing to pay a small amount for a xgrid enabled client no problem, but thats just me. It makes sense for the project I think -