What you can do to mitigate 2) is to only log in as a User, not an Admin, unless it is necessary for the specific task - and there's always Run As.
Not enough people do this ....
Don't be a lazy computer user ! 99.999999% of viruses need admin rights to infect and propagate ... just like fire needs oxygen .... remove the fuel and you're much safer (please, no smart alec replies about oxigen removal, you know the point I was trying to get accross
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The view of Gertrude the Wombat, however, about living without AV software, is just asking for trouble. Especially given free/low cost AV software is available.
Look, everyone knows that Norton is slow and memory hungry. Use something else (such as Kaspersky, F-Secure or similar) ... and all should be well.
Just my 2p worth.