I recently discovered an application for Windows called Launchy. Similar to QuickSilver for OS X, Launchy can be activated with a simple key combination and open a prompt for easily launching applications and executing files. While it's no where near as comprehensive as QuickSilver, it is no doubt a long awaited application for XP users. It also comes pre-installed with a variety of skins. You have the ability of telling Launchy to index several directories, such as your music directory, which comes in handy when looking for a song to play.