Thank you that looks like it might do the trick?
It would appear that installing Virtual Box takes care of partitioning the disk etc to use Windows.
If I want to install a programme to run in Windows is it just a case of opening Windows and then installing the software, and it will install to the Windows partition?
MarkWebb, don't take it wrong, but words are important, particularly in the tech world, so I am going to correct a few things in your post. I don't use Virtual Box, I use Parallels, but from what I see, Virtual Box operates the same way. First, VB does NOT partition the drive. What it does is to create a virtual drive, that is, a file that when VB is running, it makes it look like there is a real drive or real partition into which WIndows has been installed, and from which it is running. However, it is NOT a true partition, it's just a file. When you install a program to run in Windows, the boot process from VB will create a faked series of responses to the boot process of Windows to make it think that it's really running in a PC with a hard drive, but what it has is just the interface. VB handles all the real reading/writing to the file that is the virtual drive. When you shut down Windows, all those Windows files go back into the file, usually compressed to save storage, and if you looked at the drive structure in OS X, you won't see a windows partition because it never existed. That is the magic of virtualization!
So the better way to say your last sentence would be, "If I want to install a programme to run in Windows is it just a case of opening Windows and then installing the software and it will install to the Windows virtual drive?" And the answer to that would be, "Yes, that's how it works."
Sorry for the pedantic lesson, but as I said, in technology the proper use of words is important.