If you are seeking a overall desktop skin for Windows that resembles the overall Mac experience, I did a quick Google search and turned up this. I haven't tested this, and I am not sure if this will have a negative effect on your system.
I believe this is an icon pack that has Mac styled icons. To implement them simply visit this below site that takes you through step by step how to do that: http://www.entity.cc/how-to-icons.php
Hopefully this helps!
Edit: Also, if you download any icon packs, or software files in order to achieve any of the above solutions, I strongly suggest you scan all files with a anti virus scanner to ensure your computer remains safe.