Step 1. Delete your Minecraft.exe you currently use to launch your minecraft.
Step 2. https://mojang.com/ Go here and download the latest 1.6 version of minecraft.
Step 3. Place the download on your desktop.
Step 4. Create a new folder.
Step 5. Open your recycle bin and drag your deleted Minecraft.exe into the new folder.
You now have Minecraft 1.6 and Minecraft 1.5.2
Hope this helps guys