you might want to run any or all of the following online scanners:

ESET: http://www.eset.eu/threat-center/online-scanner (this is currently in BETA but I've tried it and it works OK)
Housecall: http://uk.trendmicro-europe.com/consumer/housecall/housecall_launch.php
Ewido: http://www.ewido.net/en/onlinescan/ or download the ewido micro scanner from http://downloads.ewido.net/ewido_micro.exe then run it from your desktop. It will download the definitions then you can run a scan. No installation needed.

Also make sure you have the latest patches for your Windows and its components: http://update.microsoft.com