Do i need Spybot Search&Destoy?

[Huskyhund]

I am running Windows Vista with built in Windows Defender and is also protected with the Windows Firewall and Kasperky Internet Security. I have used Search&Destroy for a quite some time now and do regulary searches and updates with it but... It has Never found anything suspicious. And i am starting to wonder if Search&Destory makes any difference. Maybe my computer already is safe enough with all security gizmos it already has. But i am not sure.
What do you say?

[Zenobia]

It's up to you.I have Vista with Windows Defender,also,but still use Spybot.