Trusted Internet Marketing Programs

For the money, what is the BEST anti-virus program?
Help! I’m being plagued by viruses, phishing, spam and pop-ups. My Internet browsing and email programs have slowed to a crawl. I’m in the market for a good anti-virus program. I’ve looked a lot of them, but I don’t know which one to trust. A few particulars: I’m running Windows XP and Mozilla Firefox is my browser. Here’s hoping there’s a really computer literate being out there who can help me. Thanks!
AVG Internet Security is the best paid antivirus on the market. However, you don’t want to rely on a single program to protect your PC. I typically recommend AVG Internet Security along with MalwareBytes’ Anti-Malware (free, but you can pay for a professional version).
Who is the most trusted Internet Marketing Expert online according to independent voters?