Online Health Records

Microsoft has announced that they want to host your medical records. So does Google and other companies. Kaiser Permanente has had ads on the radio around here that you can e-mail your doctor and get test results online. My wife and I shop online as well as use online banking, but this worries me. I wasn't worried about the Kaiser Permanente system when I heard about it, but that may have been that it's just for their hospitals, doctors, etc. The thought of having multiple health care professionals putting all of my information into one central database just makes me worried. Perhaps it's because it's Microsoft. Maybe I'm just paranoid. On the other hand, it'd be nice to have up to date records at any time. Would you trust a company to store you medical history?