First, you need to set windows updates to run on it's own. But I suggest to go through the update site anyway, and do optional. Important updates can show up in that list which you would not get any other way.
Anyway, you only want ONE virus scanner installed at a time. Virus scanners and interfere with each other, sometimes making both of them not function at all. So only one virus scanner.
Then it's also recommended to have a spy ware removal tool. I myself only have two(Spybot and Adaware), but you can have more.
Next is a firewall. Firewalls are really not needed, but it won't hurt if you have one, short of the resources you use on your system.
But, if you are on a router, firewalls are almost pointless.
