The best is K-Lite Mega Codec. In this package you will found all codec you want (Quick time, divx...)
DOWNLOAD LINK:
http://www.free-codecs.com/download/K_Lite_Codec_Pack.htm
The best free open source graphical editor is The GIMP. This is translate on the many languages... DOWNLOAD LINK: https://www.gimp.org/ The free windows graphical editor is PAint.net. Very cool DOWNLOAD LINK: http://forums.xisto.com/no_longer_exists/
Hmm... Well, the best free antivirus protection tool is Avast 4! Home Edition. Request free registration for virus database update. Almost detect all viruses, providing tools for protecting privacy, web filters, and Avast Virus Vault for safe handling of infected files, your may sending suspision files to Avast for analizing, and much more... DOWNLOAD LINK: https://www.avast.com/index