Well, I'm currently a very partisan NOD32 user, and it does combine a light footprint with excellent protection. But... while your system certainly meets the minimum requirements to run XP, it just won't be a pleasant experience. Personally, I would look at some of the Linux distros. I think you might be happier with the performance even if you just want to do email and browse the Web. That would also ease your AV concerns some. NOD32 is available for Linux. You might also consider AVG, Avira Antivir, and BitDefender if you go the with Linux.