Hi Darren39. That sounds like a good setup.
FYI, I'm using avast free, has worked very well here for a long time, doesn't interfere with normal operations. For this computer (Win XP sp3) I have the autosandbox feature and the browser protection turned off. Don't need them as I have Sandboxie, Spywareblaster, SpywareGuard, Outpost firewall, and Powershadow running when I am on the 'net. None of those use much memory or CPU time, and they all offer a free version.
One thing you might think about is creating a backup image and a rescue disk, using something like Macrium Reflect Free. It's
HERE Several members here use Macrium free and know a lot about it.
There are other good free backup programs, but right now I just don't remember what the other members here use.
Backup images have saved my bacon when all else failed.