I come from a Mac background where I’m able to manually edit a photo using iPhoto (adjust contrast, brightness, straighten, etc.).
I could have sworn that one of Window’s default programs was capable of that, but I can’t seem to find it. Any idea if this is possible, or am I not remembering correctly?
Windows Photo Gallery. It is a part of Windows Live Essentials, which are free downloads from Microsoft.
IMO, Google’s free Picasa is a better program.
I like Thumb Plus for basic image editing and viewing. I’ve been using it since 1998. Win 7 forced me to upgrade my older version for compatibility.
The default app I think you’re looking for is Microsoft Office Picture Manager: it’ll be in Microsoft Office > Microsoft Office Tools.
I tried that… why won’t it let me search folders for the pic I want? Instead it wants to search my entire C drive for all photos on it. What the hell? How is that even remotely useful?
Sorry Misnomer, not directed at you, as that’s a useful tip in the future.
I keep seeing this more and more with Windows where it has to search my entire drive for a photo instead of just pointing it to the folder location. 
File > Add Picture Shortcut lets you navigate directly to any folder. And then the next time you open the app, that folder will appear in the Picture Shortcuts list (which you can toggle on/off via View > Shortcuts).
Xnview is an excellent free program for what you’re looking for.
I like it quite a bit as well. Pixlr is really pretty good too and also free.