Security Suites are generally for people that have little if any computer knowledge and no desire to learn.
You can spend BIG BUCKS for a Security package and still be plagued with Trojans and Worms.
Every program in use uses power (RAM) slowing your PC down. The bigger the program is, the more power it uses. Security Suites tend to be HUGE power hogs.
Personally, I would recommend a Router (18 to 45 dollars). You can get everything else FREE.
...what else do you need?
Protection against Worms? use Windoze Update FREE
Protection against Trojans? use SpyBot Search & Destroy FREE
Protection against Viruses? use AVG or Avast among others FREE
Other than Anti-Virus and a Router (firewall) the best means of defence is knowledge!
Embrace paranoia, they ARE out to get you!