I started with Norton a long time ago and loved it. I stopped after 2004 as the rest of the products were horrible and resource hungry.
Even worse was SystemWorks.
I then moved over to NOD32 after trialling every single AV software worth mentioning. NOD32 works well, is small and uses minimal resources. It picked up a trojan once, but could not remove it.
If you want to try any Norton product from 2006 and below:
1. Only use NAV, and not SystemWorks, Internet Security etc.
2. Disable check outgoing email.
These 2 options increase speed dramatically.
I have now tried NAV2007 and love it. Uses less resources than NOD32, finds eveything and works in the background when doing a full system scan. I can highly recommend it.
Did some beta testing with Norton360 - looked good, similar to OneCare Live. I have not played with final product yet, although tempted. One thing holding me back is the fact that comprehensive suites take up lots of resources etc, when the average user only needs an AV program and and antispyware product.
Try NAV2007 - you won't be disappointed.