Do you need both Internet security and Antivirus software for a desktop/laptop?

I bought a pc laptop recently and it only has a trial version of internet security on it so I have to buy/download some type of security either before or after it expires, however I am confused on whether I need both or just one of them installed.

How do I find out if Internet Security 2010 is gone?

I used rkill.com file to close Internet Security 2010 and then scanned and deleted the malware using Malwarebytes. Everything seems to be working fine now but I want to make sure that the Malware really is gone.

what 2010 internet security program do you recommend?

My anti virus/ internet security is about to expire. I am currently running Kaspersky 2009 and wanted to know if there was a better one out there since Kaspersky is expensive.

Is Norton Internet Security a best anti virus?

I have windows 7 home premium. I am planning to install norton internet security 2008 in it. Is it a good one? Can i install norton internet security and norton 360 at once???????????
Help me…..!!!!