create an intro with an existing dvd movie?

[Noek]

Here is what I am trying to do. I created a DVD slideshow using memoriesontv. My final working dvd movie contains 8 files:

video_ts(bup)
video_ts(ifo)
video_ts(vob)
vts_01_0(bup)
vts_01_0(ifo)
vts_01_0(vbo)
vts_01_1(vbo)
vts_01_2(vob)

Now I want to add a cool movie intro (like the THX intro for example) to the very beginning of my slideshow so I copied a VTS_01_0(vob) off of one of my movies from my DVD collection(im not even sure if it is legal to do this???).
My question now is, is there a way to add this to the very beginning of my slideshow?

[GangstaMo]

A few software with First Play options can do this,the audio might differ

Also,Have a Look at MOTV prof,i think it Has a f/Play option