Question: I have many JPEG files (pictures) on my USB flash memory. I give it to my customers to look at those pictures and choose one (then I make their order based on that selection). 
I want they can look at the pictures but don't can to copy or drag-and-drop them. 
Is there such a way?

I use Windows 7.

Answer: 
In short, no. If they can look at the files, they can copy them. There is no way in Windows 7 to prevent this.
maybe outdated, but for whoever found this thread:

just make a brochure PDF that is password protected.
they still can copy it but can't deny the link between the image and your business.

and you can make them agree on non-disclosure-agreement in a contract. so your intellectual property will be kept secure.

that way when your PDF is copied and published elsewhere you'll get even more customers instead