BlackIce is pretty good for personal use but as I've read in a couple of articles it doesn't protect your system in certain instances.  You might want to read the article on dDOS attacks on that GRC.com went through.  Basically, when the creator of GRC.com wanted to investigate how the zombies worked he found out that BlackIce didn't even work against them.  I would recommend ZoneAlarm over BlackIce if security is your concern.