Pushbullet: Install Pushbullet on your smartphone (including iPhones) and your computer, and you can send files and text snippets across devices lickety-split. It's not quite as quick as Apple's Airdrop, but it works.
Get Pushbullet free here.
Google Chrome: I tried to love Microsoft Edge, the new, superfast browser included in Windows 10. But for all its many strengths, I kept having weird issues running web apps (like Business Insider's own backend), plus it doesn't support browser extensions yet. And, as an added bonus, Google Chrome already remembered all my passwords, making the cross-operating system switch a little easier.
Get Google Chrome here.
Apple iTunes: Windows 10 comes with a "Phone Companion" that lets you at least see how much memory you're using on your iPhone. But iTunes is still the best (and only official) way to manage an iPhone on a PC (even if it hasn't gotten an upgrade that makes it nice, shiny, and touch-sensitive in Windows 10).
Grab iTunes for Windows here.
Microsoft OneNote: The official Evernote app for Windows 10 kind of stinks, especially if you're using it on a touchscren computer. I'm digging using Microsoft OneNote to take handwritten notes on my laptop's touchscreen, and then having them synced to the iPhone app.
Pro tip: The OneNote app that comes with Windows 10 is actually kind of lackluster. You can grab the much more powerful and full-featured Microsoft OneNote 2013 for free here.
PhraseExpress: I'm a big fan of custom keyboard shortcuts on my Mac. PhraseExpress is a free app that takes autocorrect to the next level: You can set autocorrects that only work in specific apps, and you can set up pre-established blocks of text to use in certain situations.
Get PhraseExpress here.
Pidgin: On the Mac, I was a big fan of Adium, the beautiful, free chat program that worked with Google Chat, AOL Instant Messenger, Facebook Messenger, IRC, and a bunch of other popular messaging services. On Windows, you get Pidgin, which is based on the same technology, but without the same thick gloss of paint.
You can get Pidgin here.
Flux: Another one that I'm glad is on both Mac and Windows. Flux is an app that changes the color palette on your screen when it gets dark out to reduce eye strain and (hypothetically) make it easier to fall asleep. It sounds weird, but it works.
You can grab Flux here.
Microsoft Snip: Apple OS X has a couple of handy keyboard shortcuts for taking screenshots. Microsoft Snip, a new beta app for Windows 10, takes it a step further by letting you draw on and annotate your screenshots before sharing them with a simple link. You can even add a voice note. And it sits on the top of the screen for easy access.
You can get the beta of Microsoft Snip here.
Panda Free Antivirus 2015: Macs are famously resistant to viruses and spyware (mostly because Windows is a bigger target). That's why I recommend grabbing Panda Free Antivirus 2015, a top-scoring tool to protect you from the bad guys. Just make sure you uncheck the installation option that makes Yahoo your main search engine.
You can get Panda Free Antivirus here.
VLC: Windows 10 doesn't come with Windows Media Player, and Microsoft's official DVD player app costs $14.99 on the Windows Store (seriously) which means you'll need a little something else to watch movies. VLC is a free media player with a reputation for supporting every kind of media file under the sun.
VLC actually has a Windows Store, touch-enabled version for Windows 10, but it's not as full-featured as the regular, old-school one that you can get here.