I have Windows Vista SP1 and Windows defender came with the computer and I have Kaspersky Internet Security also. (I first was in microsoft public general for this question, wrong place ) I wanted to know if they both can run on my computer. I was told by one yes they should work well together. And then by someone who answered why use both. If they work well together why not run both of them. I like good security. What should I do? I am still learning I was told to go buy the book Vista for Dummies, and I will do so. In the mean time please help.