Our small software company is currently shipping software developed on
C++ using Microsoft Visual Studio 6.0.  We are contemplating whether
to port over to the .Net framework and develop a C++ Windows Forms
Application using Microsoft Visual Studio .Net.

To help us make this decision, we need to know the penetration rate of
the .Net Framework (1.0 and above) for current US households. 
Penetration rate on an international level and penetration rate for
businesses are also welcome, but answer must include a figure for
current US households.   Penetration rate for .Net Framework 1.0 alone
or 1.1 alone are also welcome, but answer must include a figure for
1.0 and above as a group.

Respectable references are a must.