You might also want to consider Prevx1. They will let you use it with full capabilities for 30 days as an evaluation. That should give you enough time to clean out your system. Here is the link: (http://individual.prevx.com/) Download it, install, check for the most recent update, then scan. After ther 30 days, it will still detect malware, but will no longer clean it out for you.
At my work, we use a "cocktail" of anti-virus and anti-spyware programs which do include Adaware and Spybot. When it is a serious infection, we then escalate to Symantec 10 first, and if it's really stubborn, Computer Associate's Pest Patrol. The first two are free (as you know), last two have a fee. From my experience, it is best to have more than one spyware program going on your computer in the hopes that one will catch anything the other may miss. Lastly, with whichever program(s) you decide upon, keep them up to date, and scan often- at least once a week. This is especially valid if you are surfing the Internet frequently, downloading Limewire stuff, or going to websites that you wouldn't be proud of showing off to Aunt Mabel, if you get my drift.
Also, don't forget to back up your mission critical data in just in case a virus, worm, or malware does get past your defenses and crashes your system. It is always when you haven't backed up your data that this stuff happens.
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