Matty,
After doing a little googling i think the wkvz.exe id related to the peper trojan virus.
Norton is as much use as a wet sock - get rid of it and use something like AVG, or TrendMicro Housecall, or Panda ActiveScan. They all offer free versions.
There is a dedicated Peper removal tool available for download here: http://www.bleepingcomputer.com/files/peperremover.php.
Follow the instructions on that site and you should be fine.
Tom Steventon - TBCWorkshop
September 2006