Replace date in a DateTime with another date
<p>How do you change the day part of a <code>DateTime</code> structure?</p>

<p>I have a <code>DateTime</code> with the value of 3/31/2009 8:00:00 AM and would like to change it to any other date but the time should be same. I don't need a solution to add day(s), I need to replace it with any arbitrary date.</p>

<p>How do I achieve this?</p>
