I wanted to like Windows Defender. Real-time protection, simple setup, easy to navigate. It looked good on paper.

But it turned out to be worthless. After giving it the benefit of the doubt for three months on three different PCs, I've removed it. It just plain doesn't do anything (except for consume memory and disk space). It has never, I repeat NEVER, detected any spyware when performing a scan. The real-time protection has detected four items in three months, and they were all false positives, related to a another spyware scanner's definition updates.

The most recent example is typical. Scanning with Ad-Aware SE revealed 28 instances of tracking cookies. Trend Micro's online scanner also detected 28. Spybot found 24. Windows Defender detected nothing.

The results were the same whether WinDef's real-time protection was running or not. Disabling it did not result in an increase in the number of spyware instances the other program's detected.

Windows Defender has been in beta release for years, counting its previous incarnation as Microsoft Anti-Spyware. Microsoft can try to excuse its poor performance by saying "hey, it's only a beta", but that excuse wears thin after a while. I don't have much confidence in the final product, when and if it ever arrives.

Windows Defender beta costs nothing to download and try, so you don't have to take my word for it. Try it out yourself. Just don't trust it as your only defense, if you really want to stay free of spyware.