I have freshly installed 64 bit Win 7 and 12.04 Ubuntu dual boot machine (via a wubi install). I verified that Wubi installed 64-bit Ubuntu 12.04 and I specifically downloaded and installed the 64-Bit virtualbox package from this page on the VirtualBox website.
Ubuntu 12.04 LTS ("Precise Pangolin") i386 | AMD64
(NOTE: I have a TOSHIBA c655, with an Intel Pentium chip inside, there I selected the AMD64 as instructed to on the top of the page)
When I run Virtualbox, it will only allow me to install and run 32 Bit guests (32 bit Win 7, to be specific).
I'm utterly frustrated at this point. I click on "AMD 64", but apparently it is only installing 32-bit. Any help would be greatly appreciated.