File Sizing

Guys, When encoding to Xvid using AGK I tend to make files sizes around about 15mb per minute........90 minute film 1.3gb + 400mb for AC3 sound = 1.7gb file. I am more than happy with the results but wondered if it was time to tweak??? Can I make the file size smaller without noticable loss in picture quality (42" Plasma)?? or should I be making it larger?? On some older movies (mostly 80's) I tend to stick to the 2 Channel audio track and convert to CBR MP3 256 or 320, what sort of file size allocation should I allow for that? Thanks in Advance Stace :D

zacoz is right this depends on the movie (and your TV!). As a rule of thumb I use 10Mb/min and sometimes even less. And if you're going to convert from the AC3 track at all, because maybe it's older and 2-channel only anyway, why bother w/anything but 128? I only use CBR 128kbps but I found that my standalone players don't like VBR MP3...

If you really want to tweak things, I'd recommend the full Gordian Knot. For example, some older movies will be grainy which increases the needed bitrate, so in order to lower the bitrate that would need to be cleaned up.