title: As a programmer, what do I need to worry about when moving to 64-bit windows?
body: <p>Most of my recent programming has been on 32-bit Windows using C/C++/C#/VB6 . Lately, my customers are asking if my code will run on 64-bit Windows.</p>
  
  <p>I'm wondering what legacy features I might be using that will break on 64-bit Windows? What are some real-world issues I need to think about and worry about?</p>
  
  <p>Obviously, I will test my code on the 64-bit OS, but I'd like to know what common issues to look for. I more concerned with the existing binaries, but I am open to comments about what to worry about when recompiling (where possible).</p>
  
  <p>EDIT: Here is a <a href="http://software.intel.com/en-us/articles/collection-of-examples-of-64-bit-errors-in-real-programs/" rel="noreferrer">nice list</a> of 64-bit porting bugs.</p>