What's this about an illegal copy of Windows and disconnecting from the Internet? Nope, no illegal copy here!
There are good reasons why computer security people recommend both a software and a hardware firewall program. Just after a reformat job and especially if you go online to get Service Pack 2, you are vulnerable to attack via all the security updates you lack. But Luckyboy, I've got a hardware firewall in my router and nobody knows I'm online. If they can't find me, the can't infect me, Right?
Well, if that was actually true, then you'd be right. The problem starts the second you connect to another site including Cousin Billy's update site. Anyone connected to the site you are connected to can see who's connected and they can then querry your PC. Even if you don't actively go to Cousin Billy's site or other sites when you first get online, your PC may do so via automatic update type settings. Also, by default, when you first boot up and log on under any user name the MSN Messenger starts up and if you've installed Yahoo Messenger or most of the other IM type programs, by default they connect right away as well.
The more secure you can make your PC before going online the better. This includes not just having the Service Pack 2 installed, but having Spybot installed and the Immunize thing being run as well as SpywareBlaster installed as well. They both build a no-no list of sites they will block.
The longer it takes you to get all your updates all around and get all patched up, the longer you are exposed to threats. This is why what you do BEFORE you reformat is so important. Having all your drivers and as many security updates already on disc as possible reduces your chances of picking up something you wouldn't want to tell your Mother about!
Gee Luckyboy, so doing these steps makes me completely secure?...
No, security is a relative thing and just like with your home or car, you want to make your PC just a bit more of a hassle to break into than your neighbor's PC.
And for all you wireless router types, remember to encrypt your router before going online because they work nicely and are easy to install when you first take them home. Part of the reason for this is many of the security features are by default, turned off!