suggestion noted, but chances are that some bastard's offer isn't _THE_ problem
i use norton av as well (the 2001 version; 2002 sux (the interface and its tendency to 0wnx0r ur resources(plus, i've found it to be slower))). norton loves to make itself as prevalent on ur system as possible, don't it? i think u're stuck with the slowness.
as for SP3, i don't know what the problem is, but i do know that i have uninstalled SP3 from my machine, haven't installed it since (been about 3 years), and everything's run fine.
as for uninstalling SP3, that's a bit hairier. START>SETTINGS>CONTROL PANEL>ADD/REMOVE PROGRAMS. _I_ removed anything related to SP3, but if u take that route, make sure to backup first.