You can get Netflix in Windows7 Media Center working by doing the following steps
1. In Windows 7 you have to use the new Netflix movie viewer
http://www.netflix.com2. Install the MyNetflix MCE plugin:
http://www.anpark.com3. Open the MyNetflix Configuration from the start menu when the install is done. Enter account details and test to verify.
Start-> All Programs-> MyNetFlix->MyNetFlix Config-> Enter your account details.
4. Start->All programs-> MyNetFlix that automatically starts windows media center and netflix appears.