Hey, John. Do you have the latest driver for Windows 7 installed? That was a bit of a problem for me in my Laptop. The aero effects didnt come as the latest driver for my graphic card wasnt installed.
Also as a precaution dont try the Windows Experience index without the latest drivers for Windows 7. I got a BSOD when doing that without the latest ones. If you have the latest one's try doing the Window's Experience Index and it may adjust your settings to get the aero effects.
Here is the link for the latest ones: Link