StarCraft II supports multiple aspect ratios, such as 4:3, 16:10 and 16: 9. On TL there are several threads that discuss the benefits of playing on widescreen which is prefectly demonstrated with the following picture:


Playing on widescreen allows one to see more of the battlefield and thus grants great benefits for unit control and keeping an eye on your whole base.

However, not everybody is in the lucky position to own a widescreen monitor or to afford a new one and besides, some other applications benefit from other aspects ratios.
Both Nvidea and ATI have options in their control panels that allow the user to change the resolution as desired. However, in many cases, either the GPU or the monitor scale the desired aspect ratio so that it covers the whole screen. This is highly undesirable because the image stretches in one direction. In order to overcome this problem, the user can select an option in the GPU control panel that disables scaling so a widescreen picture is displayed on a standard 4:3 monitor, offcourse with black bars covering the rest of your screen. The options to do this can be easily found in your GPU control panel.

However, disabling scaling can only be done when the GPU and monitor are digitally connected (HDMI, DVI). If your GPU and monitor are connected by VGA another solution is required.
I've done a bit of research on this and found a solution in the form of a program called PowerStrip. Probably many of you are known with this program as it programmable hardware support to a wide range of GPUs and supports multiple chipsets. PowerStrip is free to download but registration (which is not required) costs $30.

Tutorial for SC2:

General:
1. Run Powerstrip, click its icon in the Windows' system tray, click Options, click Preferences and check the options "Auto-load with Windows" and "Restore setting on startup"
2. Back to Options, click "Desktop icons" and click "Save icons placement", this will allow to restore your icons placement should a switch to a lower resolutions displace your desktop icons.

Creating the display profile to get the desired unscaled resolution:
1. Back to PowerStrip menu click "Display profiles", then "Configure", uncheck all Options and click "Advanced timing options"
2. Uncheck all Synchronization and Options options except for "Real-time adjustment" and click "Custom resolutions"
3. Check "Lock total geometry" and click the ruler and square icon above the Close button
4. Resize the black windows until the value displayed in its upper left border reaches the desired 16 resolution exactly. (Note that this is dependent on your monitor size, for an overview of resolution see this site).
5. Back in the Customs resolutions window click "Add new resolution" and accept the display to swtich to the new resolution, then click Close
6. Back to the Advanced timing options windows click Apply or OK as applicable
7. Back in the Display profiles window click on "Save as" and type a name for your new resolution, then click OK. Now you can revert to your Display defaults

Creating the application profile for StarCraft II to use the latter display resolution whenever it is launched:
1. Open PowerStrip menu, click "Application profiles" then "Configure"
2. Locate the game executable (e.g. C:\Program Files\StarCraft II\Starcraft II.exe) and check "Apply this profile whenever the program starts"
3. Click the display profiles drop down box and select the custom resolution created above
4. Click "Save as" and name your application profile

Now you can launch StarCraft II and it will run in unscaled widescreen fixed aspect ratio as intended and the display will revert to the native widescreen resolution when you close the game.


Final point of attention: Do not change other GPU settings with PowerStrip (such as gamma and clock) if you don not know what you are doing. You can boost your video performance greatly with it, but there is no protection and you can easily put settings too high, which might fry your system.