Just a quick note: if you want to determine the page size of the OS (Windows) you can use the GetSystemInfo function.


Note that MSDN recommends to use the GetNativeSystemInfo function when running in a 32 bit app on an x64 OS (and you can use the IsWow64Process function to determine that).

One example where you need to know the PageSize is when you want to create a Paging File using the NtCreatePagingFile function because this function requires that the MinimumSize and MaximumSize parameters are a multiple of the PageSize.

Some interesting links on the subject: