My code samples assume you are using the latest header files from the Platform SDK (free download), the one that includes support for Win64. If you have an older SDK then you won't have various new data types like UINT_PTR and INT_PTR and should just use UINT and INT.
I write code that is Win64-compliant as a matter of course since all code in Windows must be Win64-compliant. Writing noncompliant code is as foreign to me as it would be for a chess player to consider the ramifications of an illegal move. It doesn't even enter my mind.
The question for readers: Should I assume that everybody has the latest header files? Or should I write old-style code (that won't run on Win64)?