Vista - Problem with Mahjong

Bought a new Asus laptop and it works sweetly. Got an NVidia 8400 Graphics
Card which is supposed to be good.

Mahjong was running fine and in full screen until we inserted the Driver
disc that came with the notebook. We didn't really understand the need for
this Drivers disc, but we needed to install a particular audio driver for a
different program. As we were installing these drivers, the screen all of a
sudden changed it's resolution to the lowest level (920x640?) and we aborted
the installation of all these drivers. We have reverted back to the original
resolution (1024X something), but whenever we open up the Mahjong game, it's
resolution is always weak and is unable to expand to full screen anymore.
Prior to the game opening, a message flashes up stating that HARDWARE
ACCLERATION IS EITHER DISABLED OR NOT SUPPORTED BY YOUR VIDEOCARD DRIVER and
asks us to make sure that the HARDWARE ACCELERATION IS TURNED ON.

We've tried System Restore but for some reason that won't restore our system
to the 2 previous restore points we attempted, and we don't really understand
how the Recovery Disc is supposed to work (which we would be willing to use
because the computer is still very new and without any of our data on it yet).

Just wondering what it would take to restore our computer to the previous
settings. Have we installed a VGA driver instead of an NVIDIA driver
inadvertantly? What settings via the control panel must we alter to see
Mahjong in full screen again and be rid of our Hardware Problems? Our fear is
that with the resolution on Mahjong being weakened, we are operating a weaker
video driver, which might also hinder any attempts we may have to run more
demanding games, programs or webpages.

Any help would be much appreciated. Our computer knowledge is quite limited
when it comes to the issue of graphics cards etc.

Thanks,

Lex