If you are using a SD card reader and Windows 7, you might damage your SD cards. Microsoft released a hotfix that you should download if you are using SD cards regularly.
Especially if you enable DMA “Advanced Direct Memory Access” you are at risk of losing data or damaging your SD cards.
The Windows 7 driver for SD cards (sdbus.sys) is not programmed correctly, therefore Microsoft released a hotfix that will fix your SD card drivers.
After downloading the patch you can safely enable DMA and speed up your transfer rate.