The only good reason to use VirtualBox (the Oracle VM manager they got from Sun) is that it works on CPUs that lack "hardware virtualization" - what Intel calls "VT-x" and AMD calls "AMD-x".
A surprising number of Intel CPUs lack hardware virt support. AMD seems to have shipped it on damned near anything with two or more cores, but a lot of Intel "Pentium dual-core", "Core Duo" and even "Core 2 Duo" chips plus the lower-power stuff (Nano) lacks it.
Which leaves you stuck with VirtualBox...
If you don't know what your chip supports, google it and you'll generally find a tech specs page from Intel, AMD or whatever. Look for VT-x, AMD-x or the like if you've got something oddball.
Jim