Microsoft Calculator Plus offers conversions between different measurement units for length,area, temperature, volume ,energy ,Power,pressure Velocity,Volume,Weight and lots more . It also includes all the mathematical functions offered in Microsoft Calculator.
It can be downloaded for following URL
http://www.microsoft.com/downloads/details.aspx?FamilyID=32b0d059-b53a-4dc9-8265-da47f157c091&displaylang=en