Virtual Box installer error message on Windows 7

I have recently upgraded to Windows 7 Ultimate on one of my work machines. I wanted to install VirtualBox-3.1.2-56127-Win.exe on my recently upgraded machine.
I go to the install files and run it and get the following error message:
Virtual Box Installer – Installation of MSI failed – Error: 1603
Checked on Internet that there could be a few reasons for this “1603 “ and performed the following
- Gave the user Full control permissions over the folder and files.
- Made sure that the disk has enough space.
- The drive that I am trying to install is a physical drive.
But nothing seems to work. Should I not be installing it on my Windows 7?
