I know no one program offers complete protection against malware, but I
thought Super Anti Spyware was one of the more effective programs.

AVG detected the Trojan IRC/BackDoor.SdBot2.OUW. Before healing I ran SAS,
Spybot S&D and Adaware.

The results:
SAS found tracking cookies only.
S&D found CyberDefender in the registry.
Adaware found nothing.

Is this a particularly difficult Trojan to detect?

Cheers,
Rusty