I've just now got a new install of Windows XP Pro up and running on my shiny new hard drive, and I've gotta get me some extra protection because the condom I wrapped around the drive will only do so much.  So, without talking about price at all, what is the best virus protection around?  I'm looking for ease of use, protection from baddies, as well as minimizing the drain on my system's resources.  My computer's running very quickly right now, and I'd love to keep it that way.

Any help will of course result in positive karma coming from me to you.

BitDefender.  It's not simply antivirus, reacting to known virii.  It establishes a virtual drive and raises flags whenever something pisses it off, before that something malicious hits your actual drive.

It'll take up more in terms of resources, but it's also more proactive.

My friend swears up and down by NOD32.  It's fast, light on the resources, and finds pretty much everything.  This guy knows his shit, I'd trust his taste in antivirus. 

AVG was my go to free antivirus for the last little while but the current virus on my dads computer managed to completely uninstall it, so I'm guessing it's time to make a switch. I'm out of the loop as I've only been using a firewall and whitelisting sites on my computer. Any other recommendations or are the ones posted here still the best?

I used Penguin for a long time, but recently switched to Avast Pro. I forget exactly how much I'm paying for it right now; not much at any rate. Anyway, it runs up to seven different scanners in the background and has really unobtrusive updates. It catches practically everything.