Miz D is right, to make a decent video, you'll need to invest a lot of time into reading at least some of the guides. A lot of it can seem very daunting at first (and to be truthful, after doing it for the last 4.5 years, I still don't understand some aspects of it), but after the first few you stumble through, it starts to become second nature.
However, this shouldn't discourage you in just 'making and learning as you go' either... sometimes experience is a good teacher!
to answer some of questions posed in this thread so far:
1. there really isn't a way to 'tape over' your original DVD's (well, unless you're using copies that are burned to a RW disc). If you're using production DVD's for your source materials, short of breaking them or scratching the surface of them, you can't destroy them by copying the data off of them.
2.
www.animemusicvideos.org guides are numerous, but the two I'd suggest are:
ErMaC and AbsoluteDestiny's guides to all things audio and video version 2 and
VicBond007's Guide to Working with DVD Footage. The rest you can read at your leisure, but those are the main ones.
3. use the best sources you have available - meaning DVD's for video and CD's for audio. You have the most control with these types of sources and they have the most potential for improving quality- and yes, you can improve on DVD quality:
4. sometimes, you HAVE to do things frame by frame
5. yes, home computers have made leaps and bounds in the last few years so it's easier for the home video-making enthusiast to do pretty quality work.
and just because Miz D showed hers...
buma's vids 
It has to be something easy to understand, for the MM2 and has to tell me exactly how to take images from existing dvds, to the computer and into the MM2 program. I don't really have spare time to look through all those. 
)
