Recomended software for transcoding .mp4 to .avi

[Illrenmazou]

Everytime I play mp4 vids with 720p resoution my lag (even with Core AVC installed). My last option would be transcoding these .mp4 videos to low res .avi format and achive little quality loss. I'm a noob at this stuff so I come here to ask you guys the necessary software(s) to use in order to achieve my desired result. Thanks in advance!

[Board of Command]

There's quite a bit to explain since you don't even seem to understand the difference between codecs and containers yet.

What you're basically asking is transcoding H264 to Xvid. To do this, you'll probably need Avisynth, YAMB and meGUI. On a machine like yours, which can't handle H264 playback, encoding this stuff will be very very slow.