best way to convert mpegs to mpeg4?

[roozbeh]

Hi...
i have read almost lots of forums regarding my problem but i dont know why only,everybody is intrested in ripping dvds to mpeg4.

Anyway,
i have lots of .mpg files,vide clips,movies,cartoons,....and my hard is almost full.i was deciding to somehow convert them all to avi\mpeg4 to reduce the size and but also achieve the best quality,maybe if possible the same!

but as there are lots of codecs with lots of options and i have not very fast pc(800hz,pentium III) so i lots myself!

which codec with which options is recommended for best reduced size with almost best quality?and is it possible to achieve the exactly same quality?

[ulapines]

https://www.videohelp.com/tools?toolsearch=&s=&orderby=Name&hits=50&convert=MPG+to+DivX...+or+List+tools

[roozbeh]

but which tool?with what settings?
i already know how to use dr divx or virtualdub i just want to know how almost easily achieve the best reduced size