Not that I want to sit and watch movies over broadband in a browser from Netflix, but since I have an account and they claimed they wouldn't bill me later(as in no extra charge) I was curious.
I downloaded the Silverlight plugin. I could only get audio with Firefox 3.6 latest beta, but the new Firefox 3.5.5 seems to work fine.
For those flicks that have the play online option, it can be a good way to sample before renting the DVD. I've only tried it on Windows Seven 32 bit at this point. If you have a Netflix account it may be worth checking out. If you google you should hit an MS page with a grid of supported OS and browser combinations.