Jabber - I have AVG for virus checking and Zonealarm for firewall. I chuck Norton off the computer (which is an ordeal in itself) whenever I buy one with a pre-installed copy. Norton caused my system to blow up once when upgrading operating systems, costs too much $$$, slows my computer way down and is just plain nasty when you want to uninstall it (it leaves files and settings behind that aren't fun to locate).
Then I have the xp restore feature turned on, make a full backup once a month and incremental backups daily (to dvd - I can save about a week per disc).