i just want to add for those of us who wish to avoid phishing scams, there is a free plugin available for firefox3 and safari3 called 'google safe browsing' where google tells your machine about fake urls before your browser is sent there and you avoid the trick.
most mail servers screen the mail with clamAV these days so it is harder to catch a virus if you use a reputable ISP. You can download your own copy of clamAV if you want to to screen your incoming mail.
the biggest trick to watch out for relates to zipped attachments in mail because the AV software generally can't screen them.
be wary of downloading software from peculiar locations on the net because code can be tampered with. if you are in the habit of downloading free software as i am, you should do it only from reliable places and learn about using checksum functions.
most importantly, even the best AV software is useless if you don't run it regularly and also back up your data.
just my two cents. i hope i have helped somebody today.
-pi