Well, its possible too. But did your battery consumption higher?

And also, your graphic card already have current consumption rating. They based U series on the rating of power consumption
of your graphic card. So driver won't affect the rating. Another thing is, mostly if you use only Intel Integrated Graphic, your
nVidia driver would not be in used at all....

Maybe you should check whether your card is turn on or not.

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Added on August 25, 2010, 11:06 pm
I hope you upgrade to 4GB.

Well, the tweaking depends on you. If you want nice looking graphics, you tune up all the AA etc..
But your frame rate will suffer. And vice versa. So the best thing is you try every setting yourself
to see if without AA, it is acceptable for you. Haha

Here is the tweaking guide:
http://www.tweakguides.com/NVFORCE_1.html