hi channeal, only just read phils pm, been away from my pc for a while.
linux is a bit different than windows and usually doesn't include the needed software by default to play dvd's and so you may minimally need to install an extra piece of software called libdvdcss2.
can you link to the different versions of linux your using so i can download and test them myself to see if they play dvd's by default or what steps you may need to take to get them to work and play a dvd.
as to dualbooting then the only extra resources/strain put on the hardware is the extra bit of storage space taken up on the hard drive by the install itself.
when you boot into windows then all the ram, cpu etc. etc. is used only by the windows os and vice versa the operating systems do not run side by side and cause problems like slowing things down because only one or the other is loaded and uses the pc's hardware.
must admit though after a quick skim through the topic it does sound like the dvd drives may be failing though and why you're having problems in windows too, personally the 2 things i have needed to replace most because of failures are hard drives and cd/dvd drives.
found this link explaining mints decision to no longer include dvd playback by default and how you go about installing the needed multimedia codecs easily yourself. :- http://www.omgubuntu...ltimedia-codecs
Installing them via Menu>Sound and Video>Install Multimedia Codecs
you will probably need to do this every time you run a live os because usually nothing gets permanently saved when running a live os, but if you actually do decide to install the os and run a dual boot then you will only need to do this the once.

Edited by terry1966, 29 November 2016 - 10:31 PM.