I recently - for the 1st time - purchased an av/suite. I bought Avira based on recommendations from The Dean, and I am pleased with it.
Many configuration options, including locking of the Host file.
Also, Malawarebytes - had a glitch, though - Dean explained that to me via PM:
..."I'm guessing the reason you had trouble with the Malwarebytes download might be due to inadvertently clicking the wrong download link. There is usually a BIG download banner ad posted near the top of the download page, but it is usually for a questionable product and not Malwarebytes. I suspect this may be the case because it happened to me once, and regularly happens to people I know.
Get it here, the link is at the top right of the page:"
http://www.filehippo.com/download_malwarebytes_anti_malware/
Note that it's not for 64-bit Vista. I don't know if it works with 64-bit xp.
Prior to reading that, the local Micro Center store has a selection of popular downloads on CD - so I bought the disk for 3 bucks.
I also use Windows Defender, password-protect the BIOS, and deny browsing history in Mozilla.
I use a wired connection with a hardware firewall - as recommended by Fezmid.