Hi,
I have been using F-Secure for 8 years now, and have never had an issue with it.
However, I do NOT do mail programs, and won't have them on my computer. That is no Outlook, or Outlook Express or crappydownloader of mail! The question you have to ask yourself is ... why are you downloading garbage into your computer?
When you have that answer, you will no longer do email on your computer, and instead ALWAYS will use Webmail (on your provider's computers instead!!!!!!), and this will make your experience a lot easier to deal with all around.
There will still be an issue or two, and once a year Microsoft has a bad word or two in their code, and boom, Google and 100 other websites get into your computer through it (rootkits) and sometimes these can be a hassle, but in general, the Professional versions of Windows (for business!) are much more secure in these areas, because it could hurt their business ... in the Home editions, it's always "end-user" and not anything else. Some folks have this idea that "rootkit's" only come from porno web sites and such, but that is not the case. It is a "process" that Microsoft, Apple, and all of these anti-fuch programs use, but some companies can do it, and others can't!
So, next time, you think that pornos are hurting the internet and its security, think again!