Jerry, video on a DVD is MPEG2 codec but the file extension is .vob not .mpg. Most editing programs won't recognize .vob files but you can simply manually change the file extension to .mpg and load them in your system.
You can also get DVD ripper programs that will pull the files off the DVD automatically.
Another process, although it takes a little longer, is to hook a miniDV cam to your desktop DVD player, set your cam to VCR mode, and play the DVD while recording to your cam. Your cam will record the video in AVI format which you can then pull into your computer and play or edit. If you still have that Canon Optura50 miniDV cam it will do the passthrough.
DVD is a terrible aquisition format because of the high compression. When you compress video you are in fact discarding data. When the video/audio in decompressed in your editor the lost data cannot be recovered. There will be quality lost in the transfer and more lost again if/when you burn back to DVD and further compress the files.