Stripholderloader
if you are using a router then the firewall/Defender etc with Vista is sufficient.
WHAT!!!
Windows Defender basically looks at spyware, not virii/trojans, Windows Firewall is useless (and that is a nice description of it) as it only filters SOME things that are "inbound" and will not stop something dodgy from sending all your personal details to one of them nice phishing sites (not forgetting how a rogue piece of code can turn off the Windows Firewall, what a nice design feature) and no router will prevent you from getting a virus/trojan as they don't have the very definitions built into them that are needed to distinguish a virus/trojan from a regular file.
If you really think that is enough protection you are very much mistaken as you do not have the rather important program necessary called anti-virus which has the definitions and the capability to intercept and destroy virii/trojans before you even run them. You're leaving yourself wide open to all sorts of trouble there.