Making it secure would be a good start.
There's always a trade off between security and usability.
If you want a perfectly secure system, don't connect it to the Internet and don't load any software from unknown sources.
Windows is reasonably secure. There will always be some bugs and security holes, and Microsoft works to find and plug such holes.
You're not going to get a lot more secure OS without making a number of sacrifices.
There are also relatively few security holes in Windows that can't be avoided by a little caution on the part of the user.
However, people would rather complain that Windows is to blame when they download and run some cool program that someone they have never heard of before emailed to them despite all the warnings that such programs might be harmful.