Kaspersky is definitely one of the better security suites out there if you feel you must spend money to feel safe. Although personally, when I tried it, I found that the interface, though very informative, would be somewhat daunting to a novice who didn't understand how to interpret much of it.
On the firewall front, I would only recommend ZoneAlarm or another 3rd party firewall if you use file sharing programs. If you use the internet just to surf, play simple flash games and email, then the in-built ones in XP/Vista/7 are perfectly adequate and far far less intrusive.
It is of course, personal preference. I just think that for it's overkill for a lot of users though. You can get multiple warnings in any given session of use whilst performing basic tasks. The point at which the protection is arguably more annoying or bothersome than what it's protecting you from is where I start questioning it's usability.