NoScript will not block flash script exploits. The best security combo for Firefox is AdblockPlus+NoScript+FlashBlock. And if you are really surf paranoid, get ImgLikeOpera extension for FF too, it lets you block all graphics (to avoid rare GIF exploits).
Thank you for this tip. I use Firefox and have only run NoScript until I saw this post. I'm amazed at how much faster my ad-heavy homepage loads now. Much appreciated.