how to add subtitles w/out reencoding

I'm an avid fan of chinese martial arts movies and I get most of them here at Extratorrent.com. Would definitely prefer a hardcoded sub but most of the time the subs are in a separate file. Most of the time I use Virtualdub for syncing or embedding subtitles in my avi files but my problem is everytime I save the avi file there is a size difference from the original one most of the time lower...example when i embedded the subtitle to a 700mb file the final output would just be around 650mb. And there is also a change in quality. So is there a way of embedding the subtitle files without re-encoding? Thanks in advance for your reply...PEACE!!!

if u use vlc player u simply drag the sub srt file on the windows and they play automatically if u have advance options on urplayer activated then rcord it and ther u go video with subs OR
use convertxtodvd add the subs and burn ur laffing there dvd with subs all nice n pretty
a lot of folks dont know how to ad subs with convertx so pm me if u need assistance
ian.