Actually, it's pretty obvious if you think a bit harder. If a reviewer doesn't mention upgradeability, then you can't, as far as laptops are concerned. That's one of those "bullet points" one hears so much about. So, find a review. Here's one (not actually linked of course, just sarcasm). No mention of upgradeable graphics. Guess it's not.
Then of course, there's the manufacturer's site. You KNOW something like that will be listed if it's available.
Well heck. This seems obvious. It's part of the nForce3 chipset...so...kinda hard to upgrade. Expansion slots listed...nothing about graphics, not even nVidia's new graphics slot. (Pretty ghey choices of options too, even considering the way OEM computers are made. If you want Firewire, you have to pay for better video.)
The manual naturally also does not mention changeable graphics. And pretty much, if your OEM doesn't sell a video card upgrade, then there is no video card upgrade.