Alternatively copy the .VOB files to your hard drive. Rename the end to .MPEG or .MPG and they'll play. Use a video joiner program to join them.
You can't and they won't.
You can't usually do that (most commercial DVDs are copy protected) and even if you could they won't just rename and play as you say because they are not in MPEG format, they are in VOB (Video Object) format. They need to be ripped/converted to your hard drive. You would also need the IFO file to make sense of the chapters/subtitles etc as the VOB files are not necessarily logically structured.
To add to the confusion some VOB files
are merely encrypted MPEG2 files encyrpted to prevent copying, this may be what you're referring to. But either way you can't just copy them and play them without the right tools.
Failing this, buy a DVD player :biggrin1:
That will work, sure but involves expense and rather defeats the point don't you think?
Personally I'd back up all my vital data, and use the system restore disk. patch the system up to date and restore data and install a good DVD software player though for day to day use WMP works fine. It may take an hour or two but how long have you wasted already?