What free antivirus solutions would you recommend?

• What are the limitations?
• What are the dangers of using free versions as opposed to paid solutions? E.g. are they less reliable?

As mentioned by Tony, most of the free solutions are limited to personal use so the question will mainly focus on solutions for personal use.

See if your antivirus of choice is already listed. Chances are it is.

If you spot an answer that mentions one you already use, vote that up if you think it's a good solution.

If you know of a feature or drawback not listed, or can include experiences in dealing with it, please edit the answer accordingly.

If you know of any that can also be used at work please point this out.

This covers all Windows platforms from XP, Vista and Windows 7. If you see an existing entry that needs an update or to add your testimonial, please do.