Mars was the internal
codename for the project that became known as
MSN Explorer (the shipping name). Mars was mainly an
interface design project, and became the core design for the new UI of the upcoming consumer OS,
Windows XP. As you can see, they are very similar in concept; the
logon screens are almost
identical. This design is focused towards
consumers and ease of use.
The Mars project was formerly known as
Haley, and was very big inside of
Microsoft. It had these really neat Alien posters that said "
You've got Mars!" in spooky cheesy
sci-fi flick letters. It was really quite
cool.