Take a look at the image on the right. It’s the house my father grew up in during the 40s. The top image is from Google Earth and it’s barely legible. The bottom image is from Windows Live Local, and it looks like it might have been taken from a helicopter flying overhead. Plus the Windows site doesn’t require a download. It just runs from your browser.
A quick scan suggests that Google Earth covers more territory than Microsoft, however, so keep it handy. But for urban areas covered by Microsoft, it’s the hands down winner.