Instructions
Check your current "Starcraft" update version by going to the "Starcraft" program folder in Windows. Right-click the "Starcraft.exe" file and select Properties. The version of the file will be listed under the Details tab in the Properties window.
Visit the TeamLiquid link listed under resources to download the ChaosLauncher program. Choose the version appropriate for the version of "Starcraft" you are running. Unzip the program to any folder by right-clicking the ChaosLauncher.zip file and selecting Extract All from the menu.
Double click ChaosLauncher.exe to launch the program and an error will pop up. Click okay to remove the error then select the Settings tab. Click the icon next to the window labeled Install Path to open a folder browser. Direct the program to the folder containing your Starcraft.exe file.
Switch to the Plugins tab and check the box next to W-Mode to turn on windowed mode. Press start to begin the game.