Customize Windows 8's boot screen with Boot UI Tuner

One thing you might have noticed about Windows 8 is its new boot loader (i.e. the screen that appears shortly after you start your PC). It has a graphical interface, which is nice, but it's not great for anyone who prefers a dual- or multi-boot setup, and it also makes it a little harder to get to advanced boot options

Boot UI Tuner is a free utility that gives you greater control over Windows 8's boot options. (WARNING: When you click through to the developer's download page, make sure you don't click the blue Download button. That's an ad banner. Instead, scroll down near the bottom of the page and choose the gray Download button.)
This tiny, portable program (meaning it doesn't need to be installed—you simply run it) comes in both 32- and 64-bit versions.
When you first go to run it, you'll likely encounter interference from Windows 8's SmartScreen, which will tag it as an "unknown" program and prevent it from loading. However, you can click More Info and then Run Anyway to get things moving.
From there, it's simply a matter of selecting or de-selecting various options. For example, you can turn off three default items—Enable Windows logo, Enable messages, and Enable loading circle—in an effort to speed boot performance and minimize screen clutter.
Mostly, however, you'll probably want to enable the top two self-explanatory options: Enable advanced options of boot menu and Enable editing of boot options at startup.
If you want to go old-school, click Enable legacy boot menu to see the familiar Windows 7-style boot loader.
Once you've chosen your options, click Apply and then reboot.