I have a wide screen of high resolution and I see everything small on it. So In windows I set the display to 150%, I would like to do something similar in Ubuntu. Simply changing screen resolution to lower resolution doesn't help because Ubuntu is in a virtual machine and it simply changes the VM window to the actual resolution.
Is there a command or a simple hack that can do the trick?

EDIT: I am running Ubuntu as a VirtualBox VM on Windows 7 host.