Windows Software RAID mirror slow performance vs stand alone drive

Below are benchmarks on a mirrored 500Gb drive set using Windows 2003 software RAID mirror vs the same drive from the mirror on its own.

You can see that the software RAID completly ruins the performance reducing read and write speeds from about 100Mb/s to 15Mb/s

You might get some redundancy, but it comes at the price of having an-