It will fail over time, we do know as we have been there and tried to keep it running as well as trouble shooting with other users.
Win 8 is nothing you will ever miss having! Win 10, not so bad but no reason to make the leap as long as Win 7 works.
You can try putting your files together in VideoWave. Just pick all 4 at the same time (Add File) and load them. Make sure they are in order and Export As.
Try to find the 'Same as Original' It will be there if your clips are HD. Otherwise you can create a file, like an MP4 or an mpeg2. These will play on PC's and possibly play in a DVD/BD Player (not all accept it!). You will need to run a test file.
Creating a DVD is easy from VideoWave. Just Save the project (xxx.dmsm), close VW and open MyDVD. In MyDVD add the project file (xxx.dmsm) and burn a disc. Make sure you set it to HQ and keep discs to 1 hr for a 4.7 GB disc.