I'm affraid not, laptops are impossibly hard to upgrade beacause often all the internal parts are built as one unit, not interchangable pieces of hardware. An 8800GT would never fit, they are about one and a half inches thick.
I'm far from an expert on laptops, but from what I have picked up over the years I would assume this to be the case. There is a small chance you might be able to get it done professionally, but I wouldnt count on it.
Anyone feel free to correct me. =]
~Flash
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