UPDATE 2018-08-06: I still use this list occasionally, so I added a note about Piriform's CCleaner. (I should update the whole list, this is old.)
I volunteer for Repair Café Toronto, a part of the Repair Café movement. The idea is that rather than discarding broken things, bring them to us and we'll attempt to repair them. I'm a computer fixer: these days the commonest thing we see is Windows 7 laptops that are "slow." There are of course other computers and problems: one of the simplest fixes was a guy with a Pentium 4 desktop that was running slow: we took it outside with a can of compressed air and blew about a kilogram of dust out of the truly massive heat sink (Pentium 4s run very, very hot) and suddenly the computer was able to cool itself and was running fine again.
Normally the problem is software rather than physical: we see a lot of machines infected with spyware, malware, and viruses. I've even seen ransomware, not something I ever thought to see in real life. Fortunately the person who owned the computer, once we'd explained what was going on, said "Oh, there's nothing important on there: you can wipe the computer." Which is what we did.
Here's my (preliminary!) assembled list of software for my Repair Café days.
Finding out what's on the hard drive or what's in the computer:
- PC Wizard (2010?): second choice SIW/System Information
- Belarc Advisor - hardware, software, and drivers associated with software(?)
- SequoiaView - shows space use by files and folders, great for finding what's using up so much of the hard drive
- JDiskReport (different style, same idea - requires Java)
- WinDirStat (same - I should probably prefer this)
- MagicDisc - allows loading software from an ISO
- SlimWare Utilities SlimCleaner Free - "crowd-sourced clean and optimise your PC"
- MiniTool Partition Wizard Free Edition
- Microsoft Security Essentials - anti-virus, reasonable quality, doesn't nag
- Malwarebytes Anti-Malware - malware remover
- Spybot Search-and-Destroy - another malware remover
- Panda Antivirus - current best free "trial" anti-virus, will nag you to buy it
- CCleaner - BUT: https://betanews.com/2018/08/04/avast-pulls-the-latest-version-of-ccleaner-following-privacy-controversy/
- Eraser - securely erase old files
- LockHunter - if you can't delete a file because it's locked by an application, this should tell you what that application is
- Hiren's All in 1 BootCD
- Knoppix Live (Linux) DVD - great for testing hardware and fixing software issues entirely outside the Windows environment (but you'll need to know a bit about Linux)
- Ultimate Boot CD
- Boot Repair CD - fixes broken boot sectors for Windows or Linux
See Also: Computer Hardware Repair Toolkit