From a security standpoint, there is probably nothing worse you can do than have a suite of programs from the same company that you rely on for all your security needs. We'll just pick on Symantec/Norton for the moment.
Say you install their Norton 360 product, which uses a lot of common code. If someone finds a way to exploit that common code, then they can topple the entire suite. Even if you just figure out a way around one program, the fact that the same company developed the other programs means you have some idea of how to go about attacking the rest with a higher probability of success.
Security is about layers, and the more layers you have the better, because every individual layer is going to have holes. The idea is that if something makes it through the holes on one layer, there's not a corresponding hole at the next layer.
It takes more effort to maintain, but you should have a firewall from company A, AV software from company B, and whatever else you need should be from companies C-Z.
There's also something to be said about careful program selection. We'll pick on Microsoft here because it's easy. Reasons aside, Internet Explorer is a favorite target for malware authors, so if you use IE you should expect malware. So if you avoid Internet Explorer, you avoid all of the malware designed to target it specifically. So pick a program, if it has a history of being exploited, then maybe it'd be better to not paint a giant glow in the dark target on your back by using it.
You don't really need big expensive programs to protect your computer, because at the end of the day, YOU are going to make or break your computer's security. I don't care if you go out and buy some $10,000 Cisco IDS, if you click on a bunch of random links sent to you in emails, and other questionable activities, you WILL have security issues. No computer software or even hardware device can protect you from your own dumb self. So people who go out and spend large sums of money on security suites, it could be argued, are LESS secure because they have allowed themselves to be lulled into a false sense of security. That they have this magic program which will protect them against everything out there. Never mind the fact that there are companies that spend more on just security in a year than most of us will make in a lifetime, who still get hacked, this $200 suite will keep every evil hacker out! People who develop a mentality like that will be less secure than someone running with no security software, but is extremely cautious about what they do online.