VLC is a cool media player but if you'd rather have everything play in WMP then just install K-Lite Codec Pack Standard. It has most video codecs and works fine with WMP. But I wouldn't recommend both a codec pack and VLC since VLC already has it pre-installed.
CCleaner is a very nice application but use with caution when using the registry cleaner. You can check most of them except unused file extensions because it will delete them if you haven't used them in a while. So if you haven't unpacked a multiple RAR pack in like a couple months, your system won't remember files like .R6 or something like that. Bottom Line: CCleaner a must have to clean your system efficiently.
Recuva is a good file recover program generated by the same team that makes CCleaner so it has a similar interface as long with good reliance.
As for WinRAR or 7-zip, I have 7-Zip just because its has a faster compress & uncompression speed but its uglyyyy. The icons are not that great. That why I used Types 1.3.0 to assign new icons for my most used file compression types.
Auslogic's Disk Defrag and Registry Cleaner are also very fast and helpful to your system especially the Disk Defrag. Most Auslogic's programs work VERY well.
Lastly there about 3 other programs i have that i find helpful. Any Video Converter, TagScanner, iDump. Any Video Converter (Free Edition) is an app which has most video formats and almost all codecs to convert to, it has a variety of video sizes to convert to, video & audio bitrate edit, A/V sync edit, ect. TagScanner is to edit your audio files so that they have the artist name, album, album cover, ect embedded into the file so that when you insert them into Itunes, theres no editing. You can do all this as a whole instead of editing each one by one. Finally, iDump is a free app used to export movies & music off an iPod Nano or Classic. It doesn't work with iTouch or iPhone.
~ Jon