A new Internet law:

I haven't seen this elsewhere, so I'm claiming it as my own.

jht's law says:

If you plug a Windows box directly into a high-speed Internet connection with only factory defaults, the probability that you will be ownz0r3d rapidly approaches 1 with each passing minute before Windows Update is at least run once.

In essence, you will not survive the first day. Period.

The usage of a hardware firewall or NAT router will lower this risk back down close to a probablity of 0, assuming Windows Update is run to patch all critical holes. A current antivirus subscription will lower it further, and good anti-malware protection will lower it further still.

That law is a major premise behind my business.