You can find a million different tech sites giving recommendations for the most common programs people care about. You don't need me for those. Here are the more niche programs you might have never heard of and didn't even realize you needed.
I only know these work on Windows 7. Other OSes are up to you to figure out.
Everything - search for any folder or file on your designated drives, way faster than Windows Search since it caches everything into a database. It also supports regular expressions, if you're into that sort of thing.
SpywareBlaster - passive prevention of malware and other undesirables by blocking websites and ad/tracking cookies.
ShareX - the kitchen sink and Swiss army knife utility program for literally anything you ever want to do with screenshots or screen recordings.
ControlPad - a customizable app launcher. Meant for taking advantage of the numpad, but there's a laptop mode available too. (I use this to summon Everything.)
WinCDEmu - mounts images. Cool people use this instead of Daemon Tools Lite :)
Joplin - by far the most advanced notetaking Markdown editor I've used.
VirtuaWin - like Debian's workspaces, but for Windows. (Wow, remember when SourceForge was relevant??)
Flux - if your eyes are just as bad as mine.
Unlocker - if you can't move or delete a file because it's in use, this can help... most of the time. I've noticed it has a hard time unlocking explorer.exe whenever I want to remove hard drives and flash drives. But at least you know what program to close.
Scrivener - the only paid program on here so far. For "serious" writers who need to organize everything. "Serious" in quotes because I would otherwise imply that I'm a serious writer. It's meant to be for writing novels and such, but after using it, I think it's potentially even better for writing and organizing graduate research papers.