You can modify the registry to hide physical drives in explorer.
To do so navigate to:

-HKEY_CURRENT_USER\Software\Microsoft\Windows
\CurrentVersion\Policies\Explorer\

Create here in the right pane a new REG_BINARY [Binary_Value]
(right click , new , REG_BINARY , name it as below ) and name it:

NoDrives

Doubleclick it and enter for the drive you want to hide the corresponding
binary value according to the table below:

A: 01 00 00 00    B: 02 00 00 00     C: 04 00 00 00    D: 08 00 00 00
E: 10 00 00 00    F: 20 00 00 00     G: 40 00 00 00    H: 80 00 00 00
I: 00 01 00 00    J: 00 02 00 00     K: 00 04 00 00    L: 00 08 00 00
M: 00 10 00 00     N: 00 20 00 00    O: 00 40 00 00    P: 00 80 00 00
Q: 00 00 01 00    R: 00 00 02 00     S: 00 00 04 00    T: 00 00 08 00
U: 00 00 10 00    V: 00 00 20 00    W: 00 00 40 00    X: 00 00 80 00
Y: 00 00 00 01     Z: 00 00 00 02

Note:This needs a restart to take effect.Performing the above mentioned
hack will remove the encrypted password in XP Professional.
Do not apply it if you have any encrypted passwords.