My DVD Recorder/Video Recorder which I bought to archive some old but valued family videos onto DVDRW will record on either DVD-R or DVD+R, is there any difference in the adio-visual quality or any other reason why I should prefer one rather than the other.

I noticed, on another thread, the recommendation that, having made a DVD recording on a rewritable disc, it should be "finalised" before playing on another machine. I have just made my first dubbing from VHS videotape to DVD+RW and put the finished disc into my computer DVD drive without having finalised it, and it played perfectly. Do I assume correctly that finalising prevents further recording on that disc rather than limiting it to its "mother" machine. D.

Finalising will stop it being recorded onto anymore, but you can format it and reuse it.

+DVDs are better technically I read, but if you get a good brand either will be fine.

They do play okay on a PC.

Some machines if not all allow a degree of editing with +RW that can't be done with -RW. The principle reason for finalising an RW disc is to allow playback on other machines. Likewise a use once only disc has to be finalised to make it compatible with other machines, as stvn758 says though a PC drive will play unfinalised discs as well, if your Recorder is compatible with them DVD-RAM discs are more versatile.
With RW discs generally if you record say 3 programmes on a disc lasting 1 hour each your machine will tell you yu have 1 hour left, now erase the first programme and surprise, you still only have 1 hour left, because only the 'Index entry' is deleted the programme is still there but the recorder can't find it - RAM's don't have this problem you erase a title and it's gone allowing re use of the space.

This may seem like a silly question, but what are DVD-RAM discs? the only RAM I'm aware of is the RAM (random access memory) in my computer. I know there have been developments in disc technology, double layer being one example. I've just had a look through the Operating Instructions for my dubbing machine, a Sony RDR-VX420, and it lists all the usual types of discs, but also shows a few that "cannot be played, these include "DVD-RAMs that are not recorded in DVD Video format. Does this preclude such discs from use use on my machine, I wonder. D

I think RAM was born too late, with Sky+ and hard drive equipped recorders abounding it seems gimmicky now.

What you can do is record a TV show onto a RAM DVD and then watch it from the start as it still records it.

Along with some other editing features that can't be done with the other formats.

The answers to lots of DVD related questions can be found here A quick look at Sony's website shows no mention of DVD-RAM support so I assume what your manual means is that if someone records a Movie etc. onto RAM using a PC drive then provided it's in standard Video format your machine will probably play it.

My Panasonic EZ-25 supports +R +RW -R -RW DL and RAM it also has an SD card slot!