AnandTech offers advice on nettops and Mini-ITX systems, you can read it over here.
Ultimately, whether the Intel and/or AMD nettops will be up to task for you, your Grandma, or your computer-averse friends is best determined by using them. Brick and mortar retailers like Best Buy usually stock both Atom and AMD Fusion netbooks, which perform similarly to their desktop counterparts, so you can check out similar systems at a store near you. Do note that bloatware’s effect on less capable systems is especially pronounced, so running a 1GB netbook with an active, resource-heavy Internet security suite is just asking for poor performance. A clean install (or uninstalling bloatware) will give you a much better experience, provided no one is frequenting sites that try to hijack your PC. And with that introduction out of the way, let’s get to the builds.