If you have an Intel chipsetintegrated with Graphics Media Accelerator 4500 (GMA 4500), like the Intel Q45 Express Chipset (Intel 4 Series Express Chipset Family), you could try installing an older driver for the GMA 4500, which will allow you to choose "Maintain Aspect Ratio" in the scaling option of the "Intel Graphics and Media Control Panel" at a resolution of 1366x768. The driver you should look for is 8.15.10.2182 (15.17.9.2182). For certain Dell computers with 64-bit version of Windows, search for INTEL_MULTI-DEVICE_A07_R279357.EXE, which is provided by Dell, although it might work for non-Dell computers. For other computers with Windows 64-bit, you could try installing WinVista7_64_15173, which is found in the Intel website, but I'm not sure it will work for you, because its version 15.17.3 2104 instead of 15.17.9.2182, but since it's older, it might work for you. I haven't found version 15.17.9.2182 (8.15.10.2182) in the Intel website.
Once you have found it, uninstall your current driver using the Windows Device Manager by accessing the properties of the driver, which can be found under "Display Adapters". Then, go to the driver tab and press the uninstall button. You have to uninstall both driver and its software (the "Intel Graphics and Media Control Panel"). You want to make sure that the driver's software application (the "Intel Graphics and Media Control Panel") gets uninstalled, because if you don't uninstall it and replace it with the older one, you might not be able to see the "Maintain Aspect Ratio" at a resolution of 1366x768, even if you have installed the older driver (8.15.10.2182) !!
If the uninstallation of your current driver is successful, your screen will be at a low resolution. In addition, the "Intel Graphics Media Accelarator driver" will no longer appear in the list of Programs of the Windows Control Panel. By the way, before uninstalling, be sure to disconnect your computer from the internet, because once the uninstallation has been successful, Windows will try to install the latest driver from the internet, and you don't want that.
Now, install the Intel Graphics Media Accelerator driver 8.15.10.2182 (15.17.9.2182). This will install the driver for GMA (the integrated graphics of the chipset) as well as its software: the "Intel Graphics and Media Control Panel", which is also known as
Intel Graphics Media Accelerator driver, like the driver itself. The "Intel Graphics and Media Control Panel" is the Graphical User Interface for the properties of the GMA graphics. If the installation has been successful, you will see the "Maintain Aspect Ratio" in the scaling option of the "Intel Graphics and Media Control Panel" for a resolution of 1366x768.