WhyReboot [via] displays the list of file changes a Windows software installer plans to do after reboot, so you can decide for yourself whether you do need to reboot — if you don’t know, nine times out of ten an installer forces you to reboot for no good reason. Freeware, must-have, untested.
Currently, it does not report changes in driver, program, or service state that require a reboot in order to take effect: for instance, if an installer copies new drivers, programs, or services onto your system and configures the system so that these will be started automatically at boot or login, your system will have to be restarted. These changes are not detected by WhyReboot.
SmallWindows [via] is yet another Exposé clone for Windows, but this one has the advantage of being free and open-source (which, for a carbon copy of another operating system’s functionality, should actually be the rule). Untested as well (the less I turn my PC on, the better), but I still think the Windows XP graphics system isn’t adapted to this kind of functionality — probably only good for gamers having souped-up video cards with not-too-crummy 2D drivers (which is uncommon, as I understand it).