Not long ago I extolled the virtues of using side-by-side Windows Explorer windows to manage files and folders.
I still think that's a great way to go, but it does require you to manually open two instances of Explorer, then drag one to each side of the screen (or use keyboard shortcuts for faster Aero Snap snapping).
Another option: Windows Double Explorer, a tiny, free utility that provides two Explorer windows--each with a little more oomph than you get from Windows Explorer. (I promise that sentence makes sense. Go back and read it again.)
True to its name, Double Explorer employs a dual-pane interface, which you can view stacked or side by side. Within each pane you can create multiple tabs representing different directories on your hard drive. And you can drag any folders to the Favorites toolbar for easy access to them down the road.
Novice users will find there's a bit of a learning curve here, as not all the file/folder-management options will make immediate sense. But for seasoned users (and those willing to learn), WDE is definitely worth a look. It's a compact, installation-free bit of handyware that reminds me of the classic Total Commander.
One important note: Windows Double Explorer works in Windows 7 only. If you have an older version of the OS, the aforementioned Total Commander is a good bet.