why change a good horse
I completely agree with BBonham and similarly I never used any Ms updates for Windows XP, just Service Packs. Instead of updates I used to modify security settings substantially, disabled all unnecessary services and blocked internet access for Internet explorer. Firefox, extra configured to my requirements with excellent Ad-on Noscript serves perfectly instead of ie. For potentially risky Internet browsing Firefox is occasionally sandboxed.
I am not using any AV protection too, as it became extremely annoying with excessive automated activities, without my consent. I simply don't trust them, as they can collect too many data and parameters and system is blatantly open for their servers. Instead, I rely on strong in/out firewall which warns about any new unauthorized activity. At last and absolutely essential for security - never work in Windows as an Administrator!
Needles to say, my system never get infected, in spite of periodic checks with Malwarebytes, Spybot and manual inspection. Windows XP are/were great OS. I believe that M$ programmers are all but idiots, unfortunately with greedy shareholders breathing down their necks they can only follow the "wishes" from above.
Windows 7/8 could be OK OS's if almighty M$ in its "holly wisdom" wouldn't remove some "trivia's" that made XP more handy. Luckily Windows 7/8 remained customizable, but it takes much more time and efforts to clean out (decrapify) default "Improved Trojanic" M$ settings.
M$'s stubborn "innovative" messing with "grate new concepts" somehow remains in contrast with old good proverb - "never change a winning horse". Instead on "horses" M$ relies more on his "jockeys", "convincing" HW manufactures to "forget" winXP driver support for new machines. Shoveling tactic down customer's throats irresistibly opens "free opportunities" for new OS's.