Letting administrative level users other than 'administrator' access c$ in Windows 7

"Try adding a user to the local Administrators group via Computer Management:

You're right, it seems they've disabled local administrators from using their permissions for network shares since Vista, you can edit the registry to change this:

Click start
Type: regedit
Press enter
In the left, browse to the following folder:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\system\

Right-click a blank area in the right pane
Click New
Click DWORD Value
Type: LocalAccountTokenFilterPolicy
Double-click the item you just created
Type 1 into the box
Click OK
Restart your computer"