Can't change window/taskbar colour

Hi my problem is that I can't change the colour of my windows/taskbar. It works when I try the basic/contrast themes but not the aero ones. I am running windows7 home premium(32bitversion). I've already troubleshooted and it says I may need to get a WDDM compatible video driver, but when I attempt to update my video driver automatically it says it's already up to date. I've also tried restarting the 'themes' and 'desktop window manager session manager' but they are apparently running automatically and it still won't work. I can edit the colour and everything from the personalize window, it just doesn't take effect. Is there anyway to fix this? please help