We are all rightly concerned about the security of our Desktops and Laptops. For those who have the time, I would strongly recommend reading Fred Langa's blog at Test-driving ‘free scan’ tune-up suites
In brief, Langa mostly endorses everything that is recommeded on this Forum by the Experts with one notable exception. He recommends highly using Macecraft's free PowerTools' Lite and Macecraft's jv16 PowerTools ($30) for handling the Registry errors in Windows 7.
I hope the blog proves be very useful to those who read it.