Gary,
IMO I would run a third party firewall like PC Tools has , I do not know if it will work on vista as I do not know if it is 32 bit or 64? ask them, or I will do it for you if you desire...
Defender just tries to block or allow installs but is too slow, Tea timer from
www.safer-networking.org (spybot search and destroy) works much faster and threatfire is even (IMO) the fastest especially with the sensitivity cranked up all the way (you need permission to flush

)
BUT LOOK AT THE MORE INFO TAB TO SEE WHAT IT IS GOING TO ROUND UP AND KILL.
Zone alarm has a free version of a firewall but then again I do not know about working with vista and it has problems/conflicts with other programs. ( zone labs)
Avast does not conflict with Spyware Dr w/Antivirus and Threatfire and firewall installed.
It makes a more complete 'Package' for security
always configure new installs!
I have not found a completely 'secure' system...........
PC Tools browser defender is another that catches bugs but then again you need to ask them if it works w/your system. It is located on the main page, on the right, "PC Tools 'Lab'" log on running firefox for protection with it or IE for it, it detects your browser and offers the appropriate prog. and ask about the "LIve scanner' it runs from cd image that you burn, and scans alternative data streams (a Live cd , you boot from it)
The OSI stack in Vista is superior to XP and is a fairly secure OS
I do not like Much of anything in security from Microsoft
The internet is not a secure thing to be hooked up to

I am the freebie geek! when it comes to programs.
Phone support has been cut from PC Tools from 24/7 to business hours

everyone is pinching pennies.
Kaspersky has scanners like Avast but is not free and I am not sure about playing nice with other programs either
I hope this helps, if I seem disorganized it's the jet lag and 20hr sessions of setting up some networks.
reply if I can help you further...[

]
FYI XP still has 73% of the market....