I forgot to mention the stuff you have saved on HDs. The general porn stuff I would just do a mass delete and not look back. You probably have stuff you don't even remember having. But if there are a few videos you are especially fond of, I would save those as passworded zip files. You could even double zip them to really keep the snoops out.
If you have stuff, like softcore stuff, from sites that no longer exist, please don't delete that stuff. Instead, consider zipping it up and posting it. I and another guy have toyed around with the idea of starting a archive site of sorts to preserve defunct sites. It's something I keep meaning to ask the admin here about setting up a section where only old and removed stuff could be posted to keep it alive. I'm a bit of a amateur porn archaeologist of sorts!
So if you do have rare or hard to find stuff, please go easy on deleting it. But if it's just generic stuff you can find most places, delete away.