Top apps: Media Playback & Burning
For those of you that require a solid (free) MPEG-4 video codec, equip yourself with Xvid. With that out of the way,the most well rounded media player you'll find that is quaint and yet extremely efficient has to be VLC.

VLC media player is an open source media player that is stable, lightweight (can even run from a flash drive), it will handle virtually anything you throw at it (including partial/incomplete media files), it ignores DVD region coding, and so much more. It truly is the cream of the crop among media players although in terms of interface it's a bit bare.
That said, if you barely copy a few CDs/DVDs and want a freeware piece of software that can handle your burning, CDBurnerXP is an excellent alternative.

It always strikes me as ironic that despite the tremendous growth in PC hardware capabilities, we still seek the lightest application out there; but hey, if something that's a fraction of the bulk can stand up to the task, why not use it? For dedicated ISO burning, ImgBurn was coded by the creator of DVD Decrypter (after ultimately being forced to terminate production by Macrovision), and was built upon the optical disc burning engine of DVD Decrypter. It features support for a variety of image file formats, the ability to construct DVD and Blu-ray video discs and everything else you'd expect burning software to be able to handle.
If virtual drives are a priority, consider MagicISO (freeware).