There are several excellent free stand-alone options.
There won't be many (if any) free suites-which may be a good thing since suites generally use more system resources than stand-alone programs.
See this page here at bleeping computer for free programs. Since you mentioned Norton Internet Security, make sure you get a firewall in addition to an antivirus. Freeware Replacements For Common Commercial Apps
I use Comodo firewall, and recently switched back to AVG free antivirus and have had no issues with either one.
Just make sure you compare the features of the various free antivirus products, AVG offers email scanning. One of the listed programs doesn't, so if you use an email client you'll have to decide whether you want email scanning or not.
Another thing you can do-see if your ISP offers any type of security. Comcast offers McAfee free to it's customers, other providers may offer a discount on Norton, McAfee or whatever.
The key is to find programs that you are comfortable with. AND they also have to play nice with your computer. IF you decide to try a purchased product, go to the website of that product and if offered a trial, install it. Get a feel for how it works, and most importantly does it play nice with your system. If it slows down, ditch it and find something else.
Good luck in your quest. If you have any questions or concerns, post them here.
edited to add-if anyone else has any suggestions, please note that Rabbuk said NIS, which features antivirus and firewall. He/she will need both.
Edited by Queen-Evie, 01 September 2008 - 06:17 PM.