First, I have to figure out what the crap is. I've acquired a huge amount of dubious software lately, and I don't know why. I think it all came on the "free" CD with my digital voice recorder. Some of it is essential - others, less so. Then, I have to fight with my obsessive hoarding tendencies (which are genetic). I've spent the night on irc saying things like "someone please tell me that I don't need Sims 2 neighbourhood backups from 2006". And I apparently have 4.84 GB of Sims 2 custom content that I downloaded but haven't got round to installing! Seems like I continued to compulsively download stuff even after I was bored with playing the game. Ye gods. Then, I have to decide whether I'm keeping it or not, and if so, where I'm keeping it. It is debatable whether I need all the original .zip or .rar files for Sims 2 and other downloads, but it's definitely true that, except for the most important programs, I don't need to carry them around on the laptop.
I've also discovered that my AVG antivirus program somehow got broken or corrupted, and hasn't been checking the hard drive at regular intervals like it should. Having fixed it the hard way (*complete* uninstall, delete and reinstall - then booting up avgui.exe manually), I have downloaded all the updates and have it scanning for spyware and viruses. Various people have recommended other antivirus/antispyware programs, which I will look into once the computer's running at a sensible speed again.
This is so boring, and I want to go to bed. At least, I will as soon as everything's on the network drive. Then I can set defrag running overnight.