Newbie Question (with apologies to those who have gone before me)

Ok, as noted, I'm new at doing anything more sophisticated video-wise
than watching TV or playing a DVD. Here's my situation.

I recently had some old 16mm home movies from the '20s converted to DVD
by a professional outfit. The movies were silent, so the conversion
folks included some music on the audio track of the DVD when they did
the conversion. I now have a separate narration (in MP3 format) that
goes with the video. Here is what (I think - suggestions welcome) I'd
like to do.

I'd like to rip the video off the DVD, get rid of the music,
synchronize the video with the new audio (narration) and then record
the composite video/narration back on to a new DVD that is as
universally playable as possible, all without losing any more video or
audio fidelity than absolutely necessary (I paid a lot for a high
quality video conversion and I don't want to waste the investment).

Obviously, I'm going to need some software. Equally obviously I would
like to spend as little as possible in this process, but not at the
expense of doing it right.

I have a pretty competent system to work with - 3 Ghz Pentium 4,
XP-Pro, 1 Gig of memory, Sony DRU-810A DVD/CD Rewritable Drive, NVIDIA
GeForce FX 5200.

My question is, what software do I need to get me from where I am to
where I want to go, and what hints, tips and suggestions might anyone
here have for getting through this process as painlessly as possible.

Thanks in advance.

T.

newatthis