The Windows Aero experience you expect in Windows 7 is definitely not going to work if you are not installing the right drivers for your NVIDIA GeForce Graphics present in your computer. For this purpose NVIDIA has released a driver for your GeForce. The released Driver is GeForce Driver Release 181 Beta released on March 02, 2009. This is expected to work well for Windows 7 Beta. But some people are facing some problems with the Windows 7 RC (Release Candidate). Moreover the GeForce Versions for Laptops and Tablet PCs are not supported by this 181 driver, like the GeForce 7400. Anyhow I am going to address the solution below.
If you want to download the GeForce Driver 181 Beta, then you can see the link below. But before see the Products Supported list to know whether your product is included or not.
Anyhow even if you have installed the driver or not, please perform the steps below to update the driver you are using.
Step 1: Go to start, type Update in the Search box and open Windows Update.
Step 2: In the Windows Update page click the optional Update link.
Step 3: Now select the nVidia Driver update available and click OK to download.
If the Update is not shown then you can click Check For Update in the Windows Update page.
After downloading install the updates. You may need to restart the system for it to work. Hope this solves the problems for your graphics in Windows 7.