I never used to update, then I found out about all the things flying around the internet and got paranoid. I now realise that as long as you've got a good AV & Firewall, don't visit dodgy site and are sensible with email, you should be ok.
On the other hand, look at all the people MSBlast got, just because people don't download the critical updates.
updates for Win98, I went to the update site and downloaded all updates for Win98 then put them onto CDr just in case my wife's computer ever had a problem which required a re-install. Having BB helped a lot of course. : }