Online security is getting more difficult, as the bad guys trying to infect you change their tactics. Some of the older tools that we could rely on to do the job just don't cut it anymore.
Older Programs that haven't kept up:
Spybot Search and destoy
McAfee Antivirus/ Security Suite
Trend Micro Antivirus
Any, all in one security suite.
There are many reasons I don't like these various applications anymore. In general security suites, like Norton 360 are bloated, slow down your computer, and aren't that effective. Adaware and Spybot, just don't seem to be able to get rid of anything they find, if they do detect a infection.
Newer Programs that do work:
PC Tools Threatfire
PC Doctor Antispyware
Nod 32 Antivirus
Sunbelt Software's Vipre Antivirus
AVG Antivirus (Free)
Avast Antivirus (Free)
Returnil (Virtualizes your sessions)
WOT (Web of Trust) browser filter
Sysinternals Process Explorer,Autoruns, Rootkit Revealer
This list of programs I feel are, in general, lighter on your computers resources, and more effective at dealing with threats. Returnil isn't really an anti-malware program, but a program that virtualizes your sessions. Any changes to your system are removed when you reboot. Now this can be a pain, when you forgot you were running Returnil and downloaded a song off of Amazon or installed a new program, but its great if your just going to be surfing or if you want to keep a teenager from hosing a computer while they use it. Smit Fraud Fix is a specialized program designed to eliminate the new epidemic of phoney Anti-spyware programs out there today. The Sysinternal applications aren't new at all, but have been updated. They are incredibly useful tools to find out what's going on on your computer. They're fairly complicated looking at first glance, but after a while a user will be able to detect a process that isn't right, or not supposed to be loading on your computer at startup. Hijack This is a great tool to find out what's going on with your computer, its fairly complex to use effectively and should only be attempted by an experienced user.
I still believe that the best defense against malware is to have an ongoing backup program, preferable an automated backup to an external drive as well as periodic data backups to CDs or DVDs. Even better, a third backup to an online provider such as Carbonite or Amazon's S3 service truly keeps you ready for the the really bad infection, that you can't remove or a hardware failure, which can happen at any time.
One last thing their are many other programs out there that are effective a great site I read daily is Bill Mullins blog over on wordpress http://billmullins.wordpress.com/ Bill is a blogging machine! He comes up with an enormous number of useful free and shareware apps, I highly recommend his site.