Intel G31/G33 video won't use more than 256MB

I upgraded my Vostro 200 small form factor with 8GB RAM & a Core 2 Duo 3.16 GHz CPU.  I installed Win 7 64 bit, and any drivers that it didn't already have, I got from manufacturer's websites (because Dell doesn't have Win 7 drivers for my machine).  With the maxed out memory, I figured the onboard video would be able to "stretch its legs" but it won't use more than 256MB even when I set the BIOS settings to Max DVMT.  My BIOS version is 1.0.16 & I have the latest video driver that Intel makes for that Chipset.  Is this the best I can get?