What are your WEI scores for the graphics components? Aero is only activated if your overall WEI score is 3.0 or greater. Try downloading and installing the latest driver for your graphics card. If you reply with details of your card, I should be able to locate the driver for you.
4 x 4GB DDR3-1600 Corsair Vengeance CMZ8GX3M2A1600C9B (16GB)
Graphics card(s)
MSI GeForce GTX770 Gaming OC 2GB
Sound Card
Realtek High Definition on board solution (ALC 898)
Monitor(s) Displays
ViewSonic VA1912w Widescreen
Screen Resolution
1440x900
Hard Drives
OCZ Agility 3 120GB SATA III x2 (RAID 0)
Samsung HD501LJ 500GB SATA II x2
Hitachi HDS721010CLA332 1TB SATA II
Iomega 1.5TB Ext USB 2.0
WD 2.0TB Ext USB 3.0
You will need to add at least another 512 MB of RAM, but I would recommend at least 2 GB total. You will also need to get a new graphics card that meets the requirements above. Any new model will.
I just ran into the same issue with mys sisters laptop (yeah, THAT laptop).
Prior to the reformat, it had Aero enabled and had a base score of 2.0 , After the reformat and updates installed, it went down to 1.0 and lost the Aero. I'm leaving it off because it runs much smoother. I'm also hoping she won't notice the difference