It really depends on the 3D software you are using. Programs like Autodesk 3D Max that have Network Rendering allow you to send your model to another machine or a bank of machines to do the rendering. If you are using software where the renderer is a plug-in to your modeler and does not have Network Rendering you may have to install the modeling software on both machines which may violate your license agreement unless you purchase separate copies for both computers.
Another solution is to buy a specialized rendering appliance like a RenderDrive, but these are quite expensive.
---Max