I was thinking of going a similar route last year, when I was having problems extending my USB line. What stopped me was that the netbook I wanted to use had no setting to resume from a power failure, AND had no wake-on-lan capabilities. Most desktops, even older ones, can do both of these.
If my Home Automation PC goes down during a power outage (it is on a UPS, but it only has about an hour of runtime), I want it to come back up after the power is restored. As a fai-safe for that, another Pc of mine (also always-on) sends it a "wake on lan" command during its own boot process, as well.
If your netbook shuts down )or goes to sleep), you may have to manually turn it on or wake it back up. If you're not at home (the whole point of the Internet-connected apps), you have no way to do that.