Ok, why doesn't Windows support multiple desktops yet? Why are we forced to use a single desktop? There are third party apps available, but most of them suck and they're buggy as hell. Furthermore, why doesn't Windows support a nice feature like Expose, where you can display all windows at once and then select which you want?
When windows get stuck behind one another, they're a real pain in the ass to get back out. In OSX you can just hit F9 (or w/e) and select it. In Windows you need to either move the overlapping window or go down to the task bar and hit the icon, then select the one you want. Takes too damn long.
These are two things that are holding back Windows. They're present in OSX and Linux, so why not Windows? Let's go MS, get your **** together...