Increasingly, PCs have become as much about enjoying music and video as they have about productivity or gaming, which have always been prominent. Of course, Windows has its own solution, Windows Media Player, however there are plenty of free programs out there that provide extra functionality or even complete alternatives to Windows' integrated solutions. On the media player side of things there's iTunes for those of an Apple persuasion, while free alternatives such as MusikCube and Foobar2000 garner small but fanatic followings. Ultimately, there is so much to cover in this arena that it really deserves its own article, so instead we're going to be focussing on some other audio & video utilities.
First among them is the utterly superb TagScanner, which is the perfect tonic for those struggling to manage their burgeoning music collection. This powerful program can generated song tags for more or less any format, taking information from the filename as well as renaming files based on tag information. It takes a little learning, but with a short amount of exploration it's perfectly possible to get an awful lot out of this powerful application.
Whereas audio playback is fairly straightforward, the huge variety of video codecs in use means downloading increasingly bloated codec packs that are inclined to not play nice with each other. An easy solution is the all-in-one and completely free, VLC Media Player. It's more or less guaranteed to play any video format under the sun, while the number of operating systems supported is extensive. It's only real weakness is its reliance on hotkey shortcuts during full screen playback, with no pop up control available. For advanced users this is less of an issue, however beginners may find the transition awkward.
If so, another option is Media Player Classic. Designed to replicate the look and feel Windows Media Player 6.4, it's an overtly simple but actually very advanced media player. However, just like its inspiration it relies on codec packs to playback some file formats, of which the Combined Community Codec Pack is among the best.