Hi Oldschool777, welcome to the forum.
Rule number 1, is that you can not have more than one antivirus installed, even if one of them is disabled. (Same rule is generally applicable for firewalls, and antispyware.)
They will conflict, fight for resources, everything will be double-scanned, and at the best you’ll get a big slowdown, at the worst system freezes, and if really unlucky, a freeze when malware is actually detected, which could, ironically leave you less protected.
My preference is to use Avast (of course) but I have read some good reports about the general performance and behaviour of the 2010 versions of Norton.
If you want to find out for yourself, a fairly good strategy (if you can be bothered - it’s a bit of messing around) is to try using your computer for a week or two with one, then uninstall that one, use the appropriate removal tool (thanks to fredvries for that resource) to complete the removal, and install the next one you want to try. Spend enough time so that you can get used to the settings for each of them, and get a measure of how the computer is performing. If you’ve already paid for one, and it’s not a total POS, that might be an influence on your decision.
When removing and installing security software, it’s a good idea to get all the files you need in advance, because it’s best to go offline for the actual antivirus removal, so as not to be exposed to web threats while the computer is unprotected.
There can be as much or as little learning about what constitutes internet security as a user feels inclined to get into. Such subjects as immunizing, behaviour blocking, imaging, sandboxing/VM, and hardening can all form part of a layered security strategy. The strategy components I use include elements of most of the above, are in my signature, and have not let me down.