Hide Your Computer Drives.

Hidden drives Want to hide drives with sensitive material on them from prying eyes? You can prevent any or all disk drives from being displayed in My Computer and Explorer. It takes some Registry tweaks, which can be tricky. Check instructions at www.WE-Compute.com/registry.html if you are new to Registry editing. In the Registry navigate to HKEY__USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer. Right-click on Explorer and choose New and DWORD value. In the pane on the right, rename the new value NoDrives and double-click on it to open the Edit DWORD Value box. Click the Decimal option to select it, instead of the Hexidecimal option. Now for the complicated part. To hide a drive or drives, a number that corresponds to the drive(s) must be entered. Enter the value listed below for the drive. If multiple drives are to be hidden, add the numbers for those drives together. For example, hiding drives D and E requires a value of 24, because you are adding the value for D (8) to the value for E (16), which equals 24.
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: 67108863
The boot disk, usually the C drive, tends to show up in Explorer even if you hide it in My Computer. To bring back hidden disks, just change the value of NoDrives to 0 or delete the value altogether. Source