I've moved your post to the General topic since i'm not exactly sure what you are asking about.
You provided one question, asking if the virus protection of OneCare is good. In my opinion, it is as good as any other.
As for the firewall, there isn't anything you need to configure other than to identify the network you are on as Home/Work or Public, if you didn't already do that in Vista's Network and Sharing Center. Additional configuration may be needed if your needs extend beyond the basic defaults allowed by OneCare or if something is not working as expected. If a program is blocked, you will be given the opportunity to allow it.
-steve