again, a firewall is not a virusscanner or spamfilter.
A pure firewall (which the buildin firewall is) will hold things back which aren't supposed to connect from the outside.
Emails are allowed of course (again the firewall is not a virusscanner or a mailspamchecker), and you are the one that opens attachments in emails, not the firewall. And I don't need a virusscanner to tell me that "moremoney.zip .scr" is a virus or whatever....
So same with trojans and virusses; if you click and run a file which is in fact a virus or a trojan, it is not the firewall's fault, that's your uncommon sense (is that a word?
).
And indeed, those ads like "your pc is insecure, scan it now, click here!" or "you've won a big price, click here to collect" wont be held back, because that has nothing todo with a firewall.
But "hackers", trojans and virusses which are send directly to your PC without any mail or download protocol so to speak (like sasser, blaster, etc...) WILL be held back by the firewall.
The sad thing is, the more that big companies like Norton, etc. are developping special tools to make you even more lazier and not thinking, the more that the people will get paranoid and install all those things, while in fact, they are already well protected with their basic inbuild firewall, common virusscanner, and maybe their spamfilter. The rest should all be common sense...