With enormous update files like Norton's, I'm sure it's a pain for dialup people to keep updated. AVG has fast updates.
A friend of mine has a PC with a dial-up connection... she will not leave her computer until it is completely shut down. This can mean she sits and waits while "update 4 of 7" installs after she has told it to shut down. She gets VERY frustrated. Her computer is almost unusable for about five minutes after startup as her anti-malware updates are serially downloaded and installed.
As a result, she logs onto her computer only once a week now... which of course exacerbates the time to download and install more updates.
I am pretty sure I got the last trojans through scripts (the camels nose under the edge of the tent, heh, heh). Firefox with the NoScript add-on is very nice.