If you use
LookOut Outlook or Outlook Express still, all I can say is why? Mosey on over to this post for some excellent alternatives. Non-subscribers will only be able to see the first post in the thread, but it contains all the pertinent info.
Whatever browser and e-mail programs you decide to use, be sure to keep your Windows system updated at Windows Update and be doubly-sure you have a current version of a reputable antivirus program running like the free Avast or AVG antivirus software.