Most netbooks run an Intel Atom processor, and have Intel graphics chips.
Under your resolution properties, click the "advanced settings" hyperlink. You'll get a multi-tabbed configuration windows form. Look for a proprietary tag for your graphics driver... I have one that says "Inte(R) Graphics Media Accelerator Driver for Mobile." There is a great big button that says Graphics Properties. Click that, and you get a custom Intel application specific to Intel driver properties that may or may not be common to other graphics cards. There's an option in here, for me, for display rotation. I can "Rotate to Normal", or 90/180/270 degrees.