It happens to all digital-media hoarders: Eventually, your collection outgrows your software and management tools. If you're having a hard time tracking down files, or if your media player takes too long to load, you should consider changing your approach. Here are some tips and tools to make it easier to enjoy all that entertainment:
Tag files. This is essential for keeping track of any large collection. If you buy your tunes or videos from the iTunes store or most other large retail operations, your tags should be fine, but if you found them online or ripped them yourself, you may have to deal with gaps or bad info. MusicBrainz Picard is a great, free app for Windows, Mac and Linux that can help you quickly tag your music files. Note: though tagging any one album is quick, if you've got hundreds that need tags, it could turn into a weekend project.
Store files. If you've got hundreds of gigs of files, you may have already outsourced their storage to an external hard drive. You can make your life even easier by attaching that hard drive to a dedicated computer or going a step further and purchasing a network-ready hard drive. They're much easier to use than they were a few years ago, and can make your files easier to play from other computers, game consoles, or even remotely.
Play media. This is where things can get rough for large collections. Some players just don't know what to do with more than 10,000-20,000 files, and others just slow down to a crawl when searching or browsing. My favorite player is the free, open-source, cross-platform XBMC, though Songbird and foobar2000 are both popular choices. Be warned, though--your first scan with any new program is going to take several hours. You are much better off tagging files first (see above), because once they're all tagged, you'll just have to go through that long, painful scan again.
Stream media. Streaming your media might be the best answer for your immense collection, though once again, tagging is key here. If you want a portable music solution that can work on mobile devices and computers far from your home network, consider Audiogalaxy. It's free, but it does require you to keep a computer on at all times, or at least when you want to play your music. It takes a while to assess your library, and is limited to 200,000 songs (not much of a limit unless you're part of the 1 percent), but you can then find and play them easily from any computer, Android, or iOS device.