Q: sound but no picture on pc

Hey there Jmonien,

It sounds like you are not seeing any video when you play purchased videos from the iTunes Store but there is audio. I recommend the following article for you to help get that resolved:

Troubleshooting iTunes for Windows Vista or Windows 7 video playback performance issues

http://support.apple.com/kb/TS1718

Start with these steps, and work your way down the article as needed:

Check your system requirements

• Be sure that your computer meets the requirements to properly playback video in iTunes. These requirements are detailed on the iTunes download page.
• Check to see if you have the latest video driver updates for your computer and any installed components. For instance, video driver software updates often offer improved graphics performance for your system. ReadUpdating the drivers on your Windows PC to learn more about updating drivers on your Windows Vista PC.

Increase Display Color Quality in Windows Vista or Windows 7

• On the Start menu, click Control Panel.
• Click "Hardware and Sound" in Control Panel. Then, click Personalization in Windows Vista or "Appearance and Personalization" in Windows 7. In Windows 7, select "View by Category" if you do not see the option for "Hardware and Sound" in Control Panel.
• Alternately, in the Classic View of Control Panel, click Personalization.
• Click  Display Settings for Windows Vista or Display and then Screen Resolution for Windows 7.
• Windows Vista: Choose the highest resolution setting as shown here:
  
  
  
  ...
  
• Click OK.
• Your screen may flash briefly and you may see a message asking you to confirm the settings. Click Yes if the image on screen looks normal. Note: If the screen looks dark or distorted, wait 15 seconds for the screen to revert to it's previous state.

Thank you for using Apple Support Communities.

All the very best,

Sterling