If you wish to transcode quicktime movies (MOV, QT), please install QuickTime Alternative. If you wish to transcode RealMedia movies (RM), please install RealMedia Alternative. If you wish to transcode OGG Movies (OGM), please install OGG Media Codec.
To transcode QPEL, and other codecs, you just need a valid DIVX decodec (DIVX 5 / 6, XVID, etc). You can download XViD 1.0.3 here.
The fastest performing MPEG4 codec is MS MPeg4. So if you wish to improve performance of your system, try to use this one. Quality isn't the best, but it's sure fast.
Install K-Lite codec pack (automatic install)
Install QuickTime Alternative
Install RealMedia Alternative
Install XViD 1.0.3 codec
Install MS Mpeg4 codec
Install OGG Media codec