If you have Vista Enterprise, you need to install the drive preparation tool.
If you have Vista Ultimate, you already have the drive preparation tool. Follow the instructions below.
When you install this tool, the tool adds an item to the Start menu. To start the BitLocker Drive Preparation Tool, use one of the following methods:
After the tool finishes preparing the drive, you must restart the computer. Then you can use the Security item in Control Panel to enable BitLocker.
To encrypt drives and to verify boot integrity, BitLocker requires at least two partitions. These two partitions make up a split-load configuration. A split-load configuration separates the main operating system partition from the active system partition from which the computer starts.
The BitLocker Drive Preparation Tool automates the following processes to make the computer ready for BitLocker:
When the tool finishes, you must restart the computer to change the system volume to the newly created volume. After you restart the computer, the drive will be configured correctly for BitLocker. You may also have to initialize the Trusted Platform Module (TPM) before you turn BitLocker on.
After your computer restarts, you should return to Bitlocker:
You should make multiple copies of your encryption key. For safekeeping, make one copy to a USB key and make one copy to a folder on the machine and then email the key to a trusted source. You should then delete the key file stored in the folder you chose above.
To turn on TPM, you will need to boot into the BIOS on the computer (see manufacturer for details on BIOS access) and enable TPM in the security tab.