Look for converters that include their own codec packs so you don't have to download extra files manually. Step-by-Step: Converting Your First Video
If you tell me you are trying to convert (e.g., MOV to MP4) or which device you want to play it on, I can recommend the exact software version and settings you'll need for the best results on Windows 7. download video converter for windows 7
Convert files to formats supported by Windows Media Player. Look for converters that include their own codec
Click the "Add" or "Source" button to select your video. download video converter for windows 7
Select your desired format (MP4 is generally the safest bet for Windows 7).
Quick, occasional conversions without needing a dedicated suite. How to Safely Download and Install