Warning
I have a 2002 XP Pro and without the updates it has become extremely vulnerable to virus/spam attacks: 5 secs after connecting to the Internet the browser is rendered useless. Even after formatting the pc, installing only the modem drivers and then trying.
Installing anti spyware and antivirus residents I only achieved to replace the infection with a flood of warning/stop messages from this programs. The browser remained useless because of this (I tried Opera and IE). Haven't tried a firewall, 'cause I wasn't able to download one.
Solved the problem manually downlading at work every friggin' security update I found at Microsoft's Download Center, burning them into a cd and installing them at home.
Be careful if you do it, I would back up any critical data if I were you.
Good luck! :giddy: