Where can I download Minecraft 1.7.1 without not virus from website?

If you purchase Minecraft, you can select different game versions from the login menu when you launch the program. Just open Minecraft, and before you click play, click "Edit Profile" on the left, and it will open a new window. Once you're here, look down until you see an option for "Game Versions" and use the drop down menu to select the version you wish to play on.