To follow up on my Why Design Matters. A pictorial history of microsoft.com post (showing the microsoft.com homepage iterations dating back to 1994), TechRepublic has a great posting called Dinosaur Sightings: Windows splash screens from 1.01 to Vista

Ever since the dawn of the Windows operating system, Microsoft has used Splash Screens as a means of distracting us while the operating system is loading. In addition to their entertainment value, the Windows splash screens typically provide us with some sort of feedback on the progress of the sometimes lengthy startup process.

In this gallery, you’ll be able to browse through all the splash screens from Windows 1.01 to Windows Vista.