A good online scanner you should try is this one:

http://www.bitdefender.com/scan8/ie.html

But you need to start it from Internet Explorer in windows, if you try load it in Firefox you will get error.

You maybe also like to try three other:

http://support.f-secure.com/enu/home/ols.shtml
working with Firefox

http://www.tenebril.com/scanner/main_scan.php
working with Internet Explorer

http://www.spywareguide.com/onlinescan.php
Working with Firefox