The Netflix and Optik software a completely independent things. All the Optik software on the XBOX 360 does is interface the main HD PVR in your house. If you are only wanting to use the 360 for Netflix, then you wouldn't need the Optik software or the $5 per month.
For Netflix you would use the XBOX 360 and it would have to be attached to the tv. One thing, I do believe Netflix requires a GOLD XBOX live account.
@ac: 100% correct on the Gold requirement for Netflix on 360. I have three xbox 360's in my house (I'm using media center, and using 360's extenders) and it ticks me off a little that I need Gold to access my Netflix subscription on them.
PS3 and Wii don't require an extra payment for Netflix access, so it's a little annoying the xbox does.
If you only have one xbox, and have xbox live gold anyhow, then it's not a big deal, but as it stands I can't watch Netflix on more than one xbox at a time, since it requires I move my gamer tag from one to the other to access it.
@s2bnhm: Wouldn't it be awesome to be able to access Netflix from within the TV Guide on any old set top box for your tv service? I can access Netflix on my media center, but not on my extenders inside media center. It's in two different spots. Sadly.
I guess I can't complain too loudly though, since at least us Canadians finally have access to Netflix.