This might not be of much help to you. . . I’ve used underpowered machines as thin clients— “remote desktops”, that is, the old machine becomes a dumb graphical terminal with a mouse and keyboard, some more modern piece of hardware runs the heavy loads over the local network. In my case, light Linux distros on the laptops running X servers, shelling into a beefy Linux workstation to run the hungry apps like web browsers. There are similar solutions in the MS Windows world, though I don’t know the requirements on the thin-side.
If not, folks posting on this thread have given me food for thought for some alternatives. I love Free Republic!