I thought this was a pretty good trick to keep people out of your private files that you don't want them in.
To start out back up your registry this is very important unless you are doing this on a test machine that you don't care if you have to reload windows

Windows 98: Click on Start Run then type Scanreg in the dialog box that comes up and press Enter. When a window tells you that there are no errors, click on yes to back up the registry, and then click on ok. To restore the registry, click on start shutdown then click on restart in MS-DOS mode, and select OK.
At the C:\WINDOWS> prompt, type Scanreg /restore (there is a space before the slash) and press Enter. Select a backup from the list and press Enter again.

Windows 2000: You use Regedit's Export feature to do this click on start then run and type regedit in the dialog box that comes up and at the top click on Registry then select export registry file a new window will come up and you will have to put in a name for the back up I would name it "Registery Backup" then click on the save button and at the top click on the yellow folder that has a arrow pointing up to change where you want to save the backup file I recommend making two copies one on the hard drive and one on a floppy or Cdr/Cdrw CD (if your computer has a rewriteable drive)

Windows Me and XP: Click on Start, Programs, Accessories, System Tools, System Restore to bring up the System Restore Wizard. To back up the Registry, choose create a restore point
To restore the Registry, follow the steps above and select restore my computer to an earlier time

Once you have done the backup check it to make sure it is indeed backed up.

Now for the Magic
Click on start highlight run and type in regedit then expand the tree to


In the Explorer key folder, create a new DWORD value by right-clicking Explorer, then choosing New DWORD value. Name the value "NoDrives" (without the quotes). This value defines local and network drive visibility for each logical drive on the computer. All drives will be visible as long as this value's data is set to 0.

Following the table provided below, enter the decimal number corresponding to the drive(s) you want to hide as NoDrives value data. When you right-click on NoDrives and choose Modify, be sure that you select Decimal base, not Hexadecimal.

Drive Number to hide
A: 1
B: 2
C: 4
D: 8
E: 16
F: 32
G: 64
H: 128
I: 256
J: 512
K: 1024
L: 2048
M: 4096
N: 8192
O: 16384
P: 32768
Q: 65536
R: 131072
S: 262144
T: 524288
U: 1048576
V: 2097152
W: 4194304
X: 8388608
Y: 16777216
Z: 33554432
All drives 67108863

If you want to hide more than one drive, you just simply add the drive amounts together for a combined total.

For example, to hide the D:/ and T:/ drives, add the decimal value for the D:/ drive to the decimal value to the T:/ drive.

8 (D) + 524288 (T) = 524296

To disable all of your visible drives, set the value to 67108863.

You must reboot your PC to see your changes.