Use Free Tools Provided by Anti-virus Companies
Do you think your computer might have been compromised? No anti-virus, no problem. You can do an online virus, spyware, and malware scan using some free tools on the web.
Housecall – Mac, PC and Linux
Housecall from Trend Micro will do an online scan of your computer. Tell you what it found and makes recommendations for keeping your info private, like removing cookies and temporary Internet files. Housecall is also capable of spyware and malware detection and removal.
Kapersky Online Scanner – PC and Linux
Kapersky’s scanner also scans for malware and spyware. Seems to be a bit slow as it needs to download about 52MB virus definition files before it actually starts the scan.
BitDefender Online Scanner – PC only and must use Internet Explorer
Bitdefender also detects spyware and malware on your computer.
All of the above do not prevent viruses, spyware, or malware from infecting your computer. They are tools used to detect and clean an infected machine.
Recommend running a full scan from different anti-virus companies just to be safe. Instead of buying a product, this online solution fits well.