EDIT: Apparently the inquirer tried to sensationalize this issue by portraying it as devastating for NVidia. Not all GeForce 8 users have experienced problems (including myself on my XPS M1330): so long as you don't let your laptop get too hot, everything should be fine. By the way, Dell released a new BIOS for GeForce 8 laptops to enhance cooling, so you'll have extra protection.
Download here:
http://support.dell.com/support/downloads/download.aspx?c=us&l=en&s=gen&releaseid=R191967&SystemID=XPS_M1330&servicetag=&os=WLH&osl=en&deviceid=14178&devlib=0&typecnt=0&vercnt=7&catid=-1&impid=-1&formatcnt=1&libid=1&fileid=263515

Some important news for laptop buyers! The entire NVidia GeForce 8000 series is affected! Watch out if you are bidding for laptops with this video card series. From: http://www.theinquirer.net/gb/inquirer/news/2008/07/09/nvidia-g84-g86-bad "The short story is that all the G84 and G86 parts are bad. Period. No exceptions. All of them, mobile and desktop, use the exact same ASIC, so expect them to go south in inordinate numbers as well. There are caveats however, and we will detail those in a bit. Both of these ASICs have a rather terminal problem with unnamed substrate or bumping material, and it is heat related." Apparently, NVidia has tried to keep this issue low-profile, but Dell has already acknowledged this to be a problem. So, if you're still looking for a laptop, be wary of the ones with GeForce 8000 cards!