Run the Aero troubleshooter and it will tell you what is keeping Aero from running. Type aero in start search box to get to it: Find and Fix Problems with Transparency.
Did you right click Desktop, select Personalize and choose an Aero theme?
Rightclick Computer>Properties>Advanced Sys Settings>Performance settings to make sure transparency is enabled.
Finally, post your
driver issue in the
Drivers forum here to get help finding and installing the latest display
driver. There may be a modded
driver for that chip/card via Google. If the latest you come up with is XP, then try installing it by running Setup in compatibility mode: rightclick setup>Properties>Compatibility>set to XP SP2>Run as Admin.