Thanks everyone for your comments and pointers
Thanks as but I had mentioned that both
Thanks GermanTux for your support
Yes I have installed the mdv package prior on my old 2009 install without problems.
In fact I still had that version VirtualBox-4.0-4.0.4_70112_mdv2010.0-1.i586.rpm archived but decided to dload the latest.
So have now dloaded VirtualBox-4.1.8-75467-Linux_x86.run and it has installed without a problem.
About to reboot to 'fix' everything into place securely so thanks for all input - this forum rocks as always.
Marking as solved.