Microsoft's design uses a mobile first approach with media queries and other techniques to make it a ubiquitous experience regardless of device. The others don't. That's why it looks the worst in an ancient browser, although it arguably looks better than the other examples if you were to open the same page on an array of devices with differing dynamics.

Thanks for explaining this :). There had to be a good reason as to why Microsoft would approach IE5 this way and I was wondering why.