I now use AVG (which is actually not really free) and I also use Mailwasher which is free unless you want to pay for some advanced features. Since using these programs I have cut the amount of spam down from about 20/day to around 1/month or less. Virus infected Emails and any spam are detected and deleted/bounced at the server and never make the journey to my compter.
I like the ability to bounce unwanted emails.