Since I wasted a New Years Eve and Early New Years Day - I thought I might add something to the discussion......
Well, the Dell repair guy came at 9:30AM on Jan 1, 2009 (yup). After a service call because of heat from the NVS 135M chp, they decided (thank God I bought the expensive warranty) and came out with a new motherboard and fan. Of course my first question was - will this fix the problem? Disclosure - I was a design engineer for Intel and worked at a BIOS company.
I looked at the new and old MOBO after they pulled it out and the part numbers on the nVidia chip; could not conclude much. The new MOBO had an nVidia chip with PN G86-420-A2. Not sure if that was a new revision (stepping) of the chip, but when we eventually re-booted the system the BIOS was v11 from April. So - I am not sure if this new MOBO had a "new and improved" nVidia Quadro NVS 135M chip. All the part numbers did not yield any new data.
However - I did notice that the heat sinks for the new laptop MOBO had "revision A1" and a December, 2008 manufacture date. A good heat sink alone may be the sole fix.
After only minimal testing (my daughter's machine) the measured temps on the processor and GPU were down 10 - 18 degrees C to about 51% C. I am sure that my daughter will beat the out of it in the next few days and will find out if it is fixed. Her 'lap' top at one point had a 95 degree GPU temp!
I went back to the original 2007 nVidia driver for now; all other optons (which I tested a lot) had various issues. However - I do need to find out what the recommended Dell or nVidia driver version might be.
At the moment - things look good. Also - Kudos to the Dell support team; they did what they promised and were pretty good (assuming the problem is fixed permanently!).