Not sure what you mean by "un-draggable", but I assume that you mean that you do not want anyone to be able to right click and save pictures from your site.
You can implement several things to make it more challanging for the user, but ultimately, i do not know of a way to make it impossible. You can disable the right click context menu, but the can use a variety of developer tools to view the source of the web page.
We can go through a list, but ultimately, the user can just take a snapshot of the screen and save the pictures.
Yes, I did change my avatar into twitter :) Just to be a little goofy... next time i'll do Facebook... if they ever had a cool icon like twitter... (I used to have apple)
second, I know that even though i disable the right click ability it won't be 100% "bullet proof" but I rather have 80% people (those that know how to take images) blocked then have 100% being able to "mug" me...
I dont think you should consider working on such problem because whatever visible can be copied, Atleast I will not waste my efforts on something that works for only 15-20%. But it is just my opinion, its upto you good luck.