I have seen Norton get blamed for many PC issues that later were proven to not be Norton related. Removing the suite just frees up resources and doesn't really get to the root of the problem. Typically when a utility slows down a PC it means that it has a weakness somewhere... or something that is barely adequate to do the job (not enough memory, slow reacting drive, older processor, other software issues, etc.) A lot goes into making the AV programs leave as small a footprint as possible. There is still a core group who likes to hate the big guys... no matter what. Mostly they just sit around in their tinfoil hats and chant: Microsoft is evil. Microsoft is evil. Microsoft is evil...
You pretty much nailed the problem. A lot of the Business services customer's I work with do not have their own IT guy so they grab something at Best buy to run on their P4 1.8Ghz 512MB ram XP machine. Ends up being Norton, Kaspersky, Avast, Trendmicro, the free Mcafee we offer , or some other giant suite where they end up installing every single component.
I am telling you guys they have redesigned the NINS2009 to be very resource light...that is the main thing they tried to do with it...and it has worked...
I am using Norton Anti Virus V10 (Corporate Version) on my system. Been using it for several years. It works real well...at least for me it does.
Sounds like everyone's hate against Vista...or I guess when you install it on a computer with a P4 and 256MB of ram and it runs like shit, it means Vista sucks. (I know thread revival...)