Hi Karajorma.
your help and input are much appreciated...
I'm slightly confused about your comment about the age of the wiki instructions... as they seem to reference fairly up-to-date files... perhaps that's the only recent thing about them (i.e. reflecting current builds, etc).
I’ve been using the hardlight wiki… but have since found other resources… but your FAQ seems pretty comprehensive.
Anyhow, I've wiped and reinstalled FS2 in its default location... so the filepath doesn't have spaces in it, etc... and the game now runs via mod mode

... so thanks goes to you and your FAQ

However, in terms of doing cunning fiddling with extracted VP files, etc... I'm still a little in the dark.
my current folder structure is something like this:
freespace2\ (root)
%fs2root%\data\ - with player (i think), freddocs and cache - I believe this is just where my saved game stuff is
%fs2root%\mediavps\ - my vp files are just sitting in here
now... if I recall correctly, files found in the \data subfolder structure override that which is found in the vp files... so does this mean I do %fs2root%\mediavps\data\... with the subfolder structure such as effects, etc?
Also, maybe I'm using the app wrongly but is it not possible to extract more than one file at a time with VPMage (or perhaps another app) - some of the vps have 300 odd files in it?
As for the shockwave issue... although I was reasonably careful reading the relevant thread, I don't believe I'm getting the effects that should be occurring. Could you give me an idea of what the shockwaves should look like? For example, should it be an expanding sphere or rings or what? I did read that some people have problems with the animation cutting off prematurely, etc... so I just don't know if the things are working properly. Mine seems to do the standard fireballs / explosion… and with, I think, a couple of expanding rings.
Finally, I'm convinced that some of the game sounds aren't working... and have heard about OpenAL... but don't know whether I should install it or not, given that the sounds seem to be ok with the 3.6.7 build and vps... also I'm slightly loathe to install openAL, as I have an audigy and wonder whether openAL would conflict with my main soundcard drivers.
Thanks very much again for your assistance.
Gaz