There either must be some money to earn or people are just really bored: another Worm (or security issue) was found in the WMF file format and you could easily be infected:
"One way this might have happened, and it's a good example of how easy it is, is through Google Desktop. F-Secure has demonstrated that Google Desktop users can become infected simply by downloading an infected file. When Google Desktop indexes the file it launches the exploit."
Not bad for an attack.
I wrote a few weeks ago about a free and easy to use Antivirus program, that you might want to try, because they keep their virus information up2date and free to use for personal installations:
Free Antivirus - I know this company quite well, good stuff!
You can also do, what Matt Cutts advises in his blog and disable the affected DLL:
"regsvr32 /u shimgvw.dll"
switches that off.