|Norton antivirus is a basic antivirus and antispyware program. Internet security includes extras like a firewall, email scanner and so on.|
Most of the other antivirus companies do Internet security versions of their programs. There are better options than Norton as it can make your computer run quite slow (uses a lot of system resources). McAfee is the same.
Have a look at http://www.datadefender.net for reviews, comparisons and download links to the latest software from the major antivirus companies. All of them do free trials for 15, 30 or 60 days (depending which one) so you can try them for yourself before you buy. This route gives you better protection than the free programs out there as they will not give you 100% protection from security threats that could harm your data and invade your personal privacy. I personally recommend Kaspersky Internet Security or ESET NOD32, but check out the reviews on the http://www.datadefender.net site and make up your own mind.