The last access date is not changed even after reading the file on Windows 7

I have some files on Windows 7, and want to see what time it was that I read it this morning (February 27 morning), but when I right click on the file and choose Properties, I see

Accessed: Yesterday, Feb 26, 2011, 2:12:37PM

so I open the file to read the content again, and then open up the Properties again, and still the Accessed (date) is the same (Feb 26).

Even if I add a column to the folder for "Date Accessed", it still shows Feb 26. But today is Feb 27 and clearly I have "accessed" it... so how can I see the true last accessed date?