lx07 said:
The answer is the same. You must put USB not DVD first (or change it each power-up)

Depending what you buy (you didn't say but anything with DOS must surely be old) you need to consider the speed of your USB interface and that USB3 or SATA will be far faster than USB1 or 2.

If you are buying something with native USB3 then don't worry about it - just make sure the USB is top of the list in BIOS.

Perhaps if you say what laptop you are thinking of getting we can give a more tailored response.
Purchasing Lenovo Ideapad 130 (15) or Lenovo V330 (15)