I'm going to be setting up my new system tomorrow so I haven't done it yet, but I'm going to disable UAC and use
COMODO's security suite. Though I'll probably turn off the anti-virus portion as I rarely have a use for such a thing (FYI, the AV part is still new for them so not as great as the rest). The firewall portion is superb if you want the ability to block everything until you give it a custom or blanket rule and the defense portion essentially replaces UAC except it can actually remember your choices, heh. Unfortunately you need a bit of computer experience to know what the heck the warnings mean. If you think you understand computers, I recommend it without reservation. (Forum people say it runs like crap on cracked versions of Win7 though)
If you're an absolute noob(grandparents), it will say some stuff you don't understand but give you suggestions regardless. The entire thing is free and claims to always remain that way.