You can implement Bitlocker without a TPM however you may wish to read up
further about it. Google can be of great help there.
It is only available to Vista Ultimate users.
How can I tell whether my computer has a TPM version 1.2?
In the BitLocker control panel, click the Turn On BitLocker link. If you
receive the following error message, then either your computer does not have
a TPM version 1.2 or the BIOS is not compatible with BitLocker or with the
TPM:
A TPM was not found. A TPM is required to turn on BitLocker. If your
computer has a TPM, the contact the computer manufacturer for
BitLocker-compatible BIOS.
If you receive this error message, contact the computer manufacturer to
verify whether the computer has a TPM version 1.2, or to get a BIOS upgrade.
Can I use BitLocker on a computer without a TPM version 1.2?
Yes, you can enable BitLocker on a computer without a TPM version 1.2,
provided that the BIOS has the ability to read from a **USB flash drive in
the boot environment. This is because BitLocker will not unlock the
protected volume until BitLocker's own volume master key is first released
by either the computer's TPM or by a USB flash drive containing the
BitLocker startup key for that computer. However, computers without TPMs
will not be able to take advantage of the system integrity verification that
BitLocker can also provide.
To help determine whether a computer can read from a USB device during the
boot process, use the BitLocker System Check as part of the BitLocker setup
process. This system check performs tests to confirm that the computer can
properly read from the USB devices at the appropriate time and that the
computer meets other BitLocker requirements.
To enable BitLocker on a computer without a TPM, use Group Policy to enable
the advanced BitLocker user interface. With the advanced options enabled,
the non-TPM settings appear in the BitLocker setup wizard. For instructions
about using Group Policy to enable the advanced user options, see
http://go.microsoft.com/fwlink/?LinkId=83223.
**You can even use Bitlocker without a USB drive and enter the encryption
password manually at boot time. (I discovered that by accident).
