CNN: Opinion: Why is Microsoft worrying about Linux?
This might be a good place to start your manager. It's from
a "mainstream" source and presents a good overview of the
problems facing Microsoft without getting bogged down in too
much technical detail (or Jihad against Microsoft flamage).
Microsoft,
Designed for Insecurity
Non-Open Source Software is inherently less secure.
Do We Worry Too Much About Protecting IP?
Risks of committing your companies internal communications to a proprietary format.
Gates under fire over upgrade pricing, licence policies
The Hidden Cost Of NT
Microsoft
Licensing 6.0: Good for Microsoft, Bad for Customers
The Magic Cauldron
A business case for open source.
The IT industry is shifting away from Microsoft
Microsoft
licence policy crumbles under fire
One big happy Windows family?
Compatibility issues exist within the Microsoft product universe, and the problem is likely to get worse.
Windows NT could triple enterprise upgrade costs
Windows NT: A Reality Check
Microsoft Internet Explorer