OK I just did it by following this
UNAWAVE - Windows 7 Basic Theme transparent
It said You will need to do 1 of these 2 guides for it to work.
Theme - How to Apply Custom Themes or (I use)
Enabling Custom Themes - Windows 7
you need to use windows classic theme then logoff then logon take ownership of the aero.msstyle in C:\Windows\Resources\Themes\Aero change the name to aeroold
then put a aero theme with the taskbar changed in C:\Windows\Resources\Themes\Aero & name it aero now windows basic will change.
I tried it works (screenshot)
Jerry
PS I can change the aero.msstyle for you if you need me to get me a color.