Think of Windows in Virtualbox as being a computer within a computer. When
you install Virtualbox it allows you to run a full version of Windows inside
of the host operating system (Ubuntu or whatever). When you start the
installed Windows virtual machine, it boots up just like Windows, but it
appears in a window on your Linux desktop. As far as Windows knows it thinks
that it is being run on a drive, but it is really just running as an
application. Inside that Windows window on your desktop, you can do
everything that you can do in Windows. The key is that you need to have a
fast chip and lots of RAM. My Windows XP VM has 128 MBs of video RAM and it
is using 1 GB of memory. So it runs as fast as a computer having those
specs. You can allocate video RAm and memory that is good for whatever
hardware you have.

You can cut and paste and share folders between Windows and Linux, once you
install the guest additions. The internet connection, mouse, keyboard, sound
and CD ROMs are all shared. ISOs can be mounted as CD drives so it is easy
to install from an ISO or it can install from a CD. The down side is that
you need a Windows license not being used by another computer, but I have
thrown away dozens of Windows XP CDs and licenses over the years, so these
are not hard to come by.