These are all free online scanners  for all sorts of threats.  They will find and remove viruses, worms, spyware, adware, etc.  I like  the Trend Micro Housecall which does an all around scan.

Trend Micro
                    
Iobit 

Windows Live One Care

Threat Expert Online
                                    
Virus Total Online


An AVG Group-Ewido



Kapersky
                            
Panda
           
Bit Defender


                                                     
McCaffee Online