I have a slightly different take on this - I view them as two different applications.
A netbook is a light, portable computing device for doing email and web whilst on the road. I do very little else with it.
My laptop is so that I have enough screen resolution, disk space and CPU horsepower to run VMs and do development while sitting on the couch or on a client site.
My desktop is for when I need even more resolution, CPU horsepower, or memory than my laptop can provide. That said, I mainly use it for storage, and am actually going to be moving the services it provides to the household (CUPS, Trac) to a desktop atom board, and then it will spend most of its time asleep. I'll WOL it when I need it (either from the Trac server or my laptop), and possibly have the BIOS start it up at midnight to download podcasts, and then let it go back to sleep when idle for too long.