(OT) Open Source Virus Scanner

[paul.cour1-H+0wwilmMs3R7s880joybQ at public.gmane.org]

   Hello
   Have a Win XP machine that performed excellently for
   5 years.
   Past 4-5 days it has slowed to a crawl, and must be infected...
   Ran Spy Bot and Clamwin Virus Scanners without finding anything (???)
   Any suggestions on Open Source Virus Scanner or technique ???
   Note: have Linux boxen that performs O. K. (chuckle!)...
   regards