I haven't tested it on a Dual Boot but if XP is picking up those Drive Letters it should work. I just hid a Shared Drive on a Workstation.
Start, Run and type in Regedt32 and press Enter.
Navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer.
Right click on Explorer, and select New, DWORD value.
Name the value NoDrives.
Right click and select modify to the Edit DWORD Value.
Using the list below, type a number that corresponds to the drive you want to hide in the Value Data text box, and click OK.
Example:
A: = 1
B: = 2
C: = 4
D: = 8
E: = 16
F: = 32
Close the Registry Editor.
You must restart the PC or log out of Windows XP for the changes to register.
You can hide other drive letters that by doubling the number for each successive drive. For example, drive G: would have a value of 64.
To hide consecutive or multiple drives add the values of the drives together. To hide drives D: and E: Add their value which equals 24 as the DWORD Value.
Backup your Registry before making any changes.