Quote - But I'm perfectly happy with XP's level of security. 

I don't even use anti-virus software.  More trouble than it's worth, IME.  I've been online for 15 years now, and never had problems with malware.  I don't use Outlook or Internet Explorer. I do use a firewall...and basic common sense when it comes to e-mail attachments and the like. 

A good trojan/virus makes sure you don't even notice it's there, and trust me, they are plenty on any unprotected system. You don't need to download email atachments to grab some, if you are online that's enough for a trojan to scan your opened ports (on windows xp without a good firewall, that would be all), and get in and do it's stuff.