some things i dont understand

ok, so everything i've read about divx / xvid are that these are basically hacks of microsofts mpeg-4 technology. so why in the hell aren't they already in .mpg format? i mean why is every divx and xvid file in .avi format and thus make it necessary for all this converting that takes forever, messes up etc. also why can there not be a program made that just converts the dvd into .mpg file that is ready to burn to vcd or svcd? and if so just wondering why not. anyways, i've always used virtual dub and then tmpgenc to make my vcd and svcd files and has always worked fine. but i downloaded a xvid copy of "28 days later" the other day, i fire up virtual dub, make the .wav then go to set the split points in tmpgenc, and every time i move the arrows, it says illegal pointer operation, or it just disappears. anyone know why this is? so i looked around for another program to use and got mainconcept which is supposed to convert the audio and video at the same time. the thing just finished encoding, and a few minutes into it on playback test with winamp and media player, the picture freezes up but the sound keeps going. ive converted other xvid files just fine using tmpgenc, but for some reason this one is really screwing with these programs. this is a huge headache, way more thanits worth for the long download searching for programs, encoding time etc. lol. also one other question, besides virtual dub / tmpegenc, is there any good program that will just convert both aud / vid and set the split point also?

 

ok one other thing im not clear on is on this mainconcept program it gives the option to convert from avi to mpg1 mpg2 vcd or svcd.. now isnt svcd already mpg2 and vcd already mpg1? so whats the difference here? lol the avi > svcd converter sets the output .mpg file at 480x 480 res. and 44100 hz sound and the avi > mpg2 converter sets it at it at 512x288 and 48000 hz. ahh it just gets more confusing.. lol