I want complete security against viruses so that my laptop runs well
There is no such thing as complete security unless you never use it. No single product is 100% foolproof
and can prevent, detect and remove all threats at any given time.
I'm not an advocate of suites. All-in-one tools and suites generally use more system resources than separate programs that do the same task. They tend to have varying degrees of strengths and weaknesses for each feature. In contrast, separate tools are designed, built and maintained with a greater focus in a specific area so they are generally of better quality and more effective at what they are designed to do. This means the program's performance for that particular feature is usually superior than their all-in-one counterpart. Further, all-in-one tools generally do not allow the user as much flexibility in tailoring default settings and usage.
If you're not using Windows XP, IMO there is no need to replace Windows Firewall with another one. Read Choosing a Firewall