GMA X3100 found in GM965 is practically useless in anything 3D. HD3200 as found in RS780M is ok for older DX7 and DX8 games I think.
The problem with discrete graphics has always been battery life under desktop/2D mode compared to intergrated. To solve that the latest development is in using hybrid graphics. Intel's GM45 provides such function when pair with a discrete GPU. e.g. ThinkPad T400 with GM45 + HD3450
When plugged into main it'll switch to the HD3450 and when on battery it'll use X4500HD, all this is done dynamically without the need to reboot.