I say bring back the Program Manager to replace the Start Menu. Its app icon would be where the Start orb is now. Similar to your suggestion, it would a central app to find, install, uninstall, update, organize and launch apps. Commonly used apps would of
course be dragged to the taskbar. handle update notification and install/update progress like the iPhone, with little red badges and on-icon progress bars.
In early Windows 7 builds there was something called a "Programs Explorer":