This post is old, but I had a similar experience recently. I found a great link which provided the info below. Works great on Vista, Win 7, Windows 2008 Server (tested), and likely Windows 2003 Server. Saved me a TON of time, all other solutions I found were NO WAY near as simple as this.
Go into the registry using regedit and change each of the "start" values in the registry keys below from 3 to 0 and this will allow you to change between the different modes by just changing the option in your bios each time you reboot.
You might not have the last registry key (iastor) as this is installed in the registry with the intel raid drivers, the default windows 7 raid driver uses the iastorV key.