It's highly recommended to protect your computer against Virus, Malware, Spyware and other potential threats. Microsoft Security Essentials is one of the better, free solutions.
Nice little program that enables you to close all your opened applications and windows with one single click. It works in Windows XP and Windows 7 and doesn't need installing.
If you want to put your video files online using HTML5 then it's recommended to have three different formats for a full browser support. Those formats are mp4, ogv and webm.
If any file can not be deleted, then you can use the program LockHunter, which removes the active connections of other applications to that file, which allow you to change or delete file.
