To disable autoplay,
Go into My Computer/right click on the external hard drives icon/then choose properties from the menu/then on the window that appears left click on the AUTOPLAY tab. On the window that appears, left click on the SELECT AN ACTION TO PERFORM, below this you can choose to open folder to view files etc there is a few others but you need to left click on TAKE NO ACTION. Repeat the above for all the options in the little drop down menu towards the top of the window for, MUSIC FILES, PICTURES, VIDEO FILES, MIXED CONTENT. When you have done this click on APPLY, you may need to restart the pc, after you have done this try and see if the autoplay has been disabled.
I would say your laptop should be safe as long as you do not choose an infected file and then copy it on to your laptop, but someone else may know better than me.