Here are some highly rated security programs:
http://www.pcmag.com/article2/0,2817,2372364,00.asp
Links to free trials of the top three:
http://www.webroot.com/us/en/home/products/trials/isp?trpd=WSAI&loc=USA
http://www.bitdefender.com/Downloads/
http://usa.kaspersky.com/downloads/free-home-trials/total-security
After you complete your scan and have a disinfected computer, install a high rated free security program such as Panda:
http://www.cloudantivirus.com/en/
Then uninstall the trial program. You may have to do that before the free security program will install.
Yes, this requires is a certain amount of work, but you should never have let your computer onto the Internet without security software, and this way you let two independent programs try to fix the damage. Don't be too confident that they will succeed. Some of the new viruses are ridiculously hard to eliminate.
I run a lot of free programs, such as Avast, Spyware Blaster, Zemana anti-logger, Comodo firewall, Malwarebytes anti-exploit free, and then have a few that I use just for scans, like Malwarebytes, GlaryUtilities, Superantispyware, Loaris Trojan Remover, Unhackme, and a number of things for the browser.
I also like to occasionally use free online scanners to mix things up and get the benefits of competition.
I try to tell people that security software and scanning is kind of fun.
When ones computer isn’t being used, it may as well be doing a silent scan, and even scanning while one is using the computer, isn’t usually an issue, unless the computer is really slow.
I also suggest putting all of the settings at their deepest levels, and only using the fullest, deepest scan setting.
Scanning, defraging, cleaning temporary files and cookies, chkdsk, keeping up with software and driver updates, all those things make for a lean, clean, machine.