Best antivirus, antispyware, and just antimalware in general.
Just doing a bit of research on my own to figure out what antivirus programs I want to use once I do a clean install of Windows 7 on my laptop. Obviously, I cannot personally try them all, so I'm going to be listing ones I find most mentioned and in general what people say about them.
Free Antivirus Software
Avast (Free) - Solid antivirus with high detection. Long reputation.
Avira (Free Edition) - Simple user interface. Started out especially strong in 2008. Solid virus detection, on par with Avast, but tends to have false alarms (false positives) as a reputation.
*Updated 2011: Unfortunately, can't recommend this anymore. Was running MSE on my laptop and Norton on another; twice this year the laptop got infected and had to clean by scanning with the Norton software instead.
Microsoft Security Essentials (MSE) - See above.
Misc. Free Tools
MBRCheck - Checks a drive for corrupted master-boot-records. Useful if your computer isn't booting up and you can take out the drive to check on another computer.
Commercial Antivirus Software
Norton Internet Security - Used to be a system hog but it's improved a lot since the 2009 version. Use it primarily now; have never had a virus on the computer this was installed on.
ESET Nod32 - Lightweight, supposedly gaining stronger repuation last few years.
Kaspersky - Full featured, heavy-duty. Not light but very robust.
Added on Jun 17, 2010 | Last Updated Jan 15, 2012