3ivx D4, H.264, and RealMagic codecs are total crap, DivX and XviD slow down the whole system (50-70 percent of cpu power for decoding on my pIII 550 with 256 ram). the only good codec is the microsoft one, the good news is it can decode divx if one changes the header of the avi file from divx to ms mpeg4. the bad news is it can't decode xvid, because this stupid format changes all the time and has become incompatible with other codecs incl. divx and ms mpeg4. those open source freaks always whimper that MS doesn't care about others and sets its own standards, like with IE, but here we have an open source project and what happens? exactly the same shit: their codec is not compatible with MS mpeg 4. and why not? There is an mpeg4 standard, isn't it? so if there is a standard, then theoretically decoding of a video encoded with one codec should be possible with another codec. since this is not the case, xvid can't be called mpeg4, because it doesn't stick to the standards. bottomline: xvid is slow, incompatible and often kills other codecs, like many people complained that after installing xvid their divx videos started playing upside down. good joke.