Hey thanks for all the pointers on this people, its really helpful.
I've just got started looking into 'demo construction kit', found here: http://www.pouet.net/prod.php?which=13382
Hopefully it'll be a good start to get my head around how it all works & take things from there. I'll also take a good look at Douglas AGT, DHS Falcon & ASM in course, thanks for those links too.
Depending on how involved I get with it, I'd like to get fully stuck in & make some quality demos as seperate productions, but for now it'd be great to make some material for my visuals. I can see yet another time consuming hobby forming for myself here! haha, cheers