I like Malwarebytes to get rid of the nasty malware and have Norton Internet Security for antivirus. I can recommend avast! as a free antivirus...
I've got Vista on all of the machines I own that will run it. No problems and I like it. I don't see any reason to upgrade if you like XP....
I've got Avast on half and Norton on the other half. I like Norton but its pricey.
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