You can pick up OneCare at retail for much less that the list price charged for an online purchase from Microsoft. The special offer for 29.95 appears to be something that happens via OneCare when it is in trial mode and the link you are presented with at that time needs to be acted on then or you don't get it again. Going to the
http://onecare.live.com site will net you the full retail subscription if you don't follow the offer from within the OneCare dialog.
Note that Amazon has OneCare for 19.99 plus shipping. You only need the retail PIN/Key inside the box to activate/subscribe from an installed trial copy - no need to reinstall.
As for your final question - the protection is good. No protection suite is perfect and you can see many reports of missed infections or incomplete removals in the virus and spyware topic folder here, but I can tell you that I personally run OneCare on many machines. My wife's PC was recently infected despite OneCare's protection, but that is one incident in almost 2 years on her machine. I consider that to be quite good.
-steve
Microsoft MVP Windows Live / Windows Live OneCare Forum Moderator
