i believe i am the exception when it comes to people who use windows, but i have:
a) never used virus prevention program
and
b) never had a virus.

practice common sense when downloading and using software on a windows machine. this should be your credo.

if you are really worried, you should read and follow the instructions given on another post about "how to secure your wallet".
basically you create a new "savings" wallet on a known virus-free OS and back it up. you should only SEND money to it, and should only ACCESS it from a known virus-free os.

p.s. i have a program that will generate 50382 FREE BTC! PM ME FOR LENK TEU DOWNLOEDS!9