The cutoff resolution for your design should be one that is common and not too big; I don't see the problem with 1024x768 or even smaller unless your application is very minimalistic, and even then I wouldn't design beyond 1200x1024.
Always keep in mind that, at any given time, we can only read an area of about two inches in diameter (ie, the average distance between the centers of our eyes when looking straight ahead). For all intents and purposes, everything outside of this area is imperceivable. The reason for this trait is our evolution as top-tier, land-based predators: our central vision is very sharp (for locking and stalking) but also very limited in area and our peripheral vision is very poor.
So if you design an application that fills a 1920x1080 resolution for example, you are forcing users to rotate their eyeballs more than necessary, which causes physical strain. Worse, you are almost certainly putting possibly relevant elements outside the users' visual sweet spot. Again, unless the application is something that is pure text and only has a few columns, pick a resolution that keeps everything fairly close together.