Originally Posted by Nicolas

That said, my home computer running IE7 on winXP with nothing but microsoft firewall, avira antivir, microsoft defender and IE7's own safety functions -so not even the google toolbar blocker, which is not necessary anymore in IE7- stays very clean, while this work PC running Firefox on Linux always makes my mailbox starting to suddenly receive and send spam. I don't even want to know what happens to the rest of the computer.

Now IE5.5 is older so less safe than IE7, but the same goes for installing old versions of other browsers. Arguments like "use this or that, you're safe" tend to have more exceptions than confirmations.