Yes, I think that Malwarebytes is a major omission as is A-Squared. I use those along with SpyBot, as I think the combo covers most things.

For an AV I tend to use Avira (I still run some Win2000 boxes) or Avast! The Avira product is quite good as it seems to have a full set of options and controls, but you need to be careful of false positives if you set it into paranoid mode

I have come across a new product from "TallEmu" (don't look at me like that......I didn't come up with the name) called "online armor". There is a firewall and a program control element. With the program control you have to tell it what you think of anything new that turns up, and it will remember your decisions. It also has some sort of sandboxing facility to run stuff in restricted mode, if you are not quite sure. It gives you UAC type (or better) protection and works on Win 2000 and XP.

More about it here:

http://www.tallemu.com/products-online-armor-free.php