Load Boxee.tv in your URL bar, and go to the "Services" section.
Check Netflix, and select "Connect." Authorize your Netflix account with Boxee by agreeing to the terms, and hit "Authorize" and "Yes, Link This Account."
Go to Microsoft.com, and download the latest version of Silverlight if you do not have it already. Click "Run" when the browser prompts you to run or save "Siverlight.exe." When the download is complete, click "Run" again.
Log into Boxee, and click on "Apps" in the home screen. Select Netflix, and click "Start."