I've seen a couple of reports that this limit was removed in the final release. Can anyone confirm this?
According to Microsoft Aero will be enabled in Windows 7 if a DirectX 9 compatible GPU with a minimum of 128 MB of Video RAM is detected.
I installed Win7 earlier today and can confirm that it is not available on my old MacBook with GMA 950 GPU with 64MB RAM.
While I can't say for sure because I don't have a mac with a video card that poor, I can say that I don't see any such limitation spelled out in the beta copy docs or options.