You can hide any of drive(s) by just adding two keys in windows registry

goto start>run
Type regedit and press enter. This will bring you to the registry editor.To hide any drive you have to follow these 2 steps
STEP1: Hidding Drive
goto HKEY_CURRENT_USER\Software\Microsoft\Windows\Curre ntVersion\Policies\Explorer now create a new DWORD value NoDrives and set its value as

2^(Alpha Number of Drive Letter-1)
where Alpha number are simple counting of alphabets from A to Z as 1 – 26

for example: to hide C drive
Alpha number of C is 3 so 2^(3-1) = 4 (decimal value)

If you want to hide more than one drive than calculate the value of each drive as explained and then set sum of those numbers as value

Alternative:
Use TweakUI for Windows XP

Under My Computer->Drives. Uncheck the drive you want to hide and click OK.

Step2: Prevent Access to the drive
Now as we have make our drive invisbble but it is still accesible so to lock the drive we will create another DWORD value at

HKEY_CURRENT_USER\Software\Microsoft\Windows\Curre ntVersion\Policies\Explorer
create a new DWORD value NoViewOnDrive and set its value same as you have calculated for hidding the drive(s)

Now your drive is locked. If you want to unlock and unhidden the drive then just delete these two keys and your drive is again accessible. You can also create two .reg files one for hidding and locking and another one for unlocking and unhidding