e1705 with 7900gs artifact problems

I've enjoyed my E1705 so far with the 7900GS, but I think it is starting to die, and I'm just finding out why everyone complains about Dell Customer Support.

I bought the computer as a budget gaming notebook to take on the road, and it did find until recently.  About 5-20 minutes into a game (WoW, AoC, Oblivion, Fallout 3, The Witcher, Warhammer online, etc) and even occasionally while browsing photos on the hard drive, I'll start to get artifacts- lines accross the screen; walls, branches, and other ingame objects also stretch out and have artifacts.  Sometimes, the screen will just turn "plaid" .

My warranty with return to depot  is good, and I've tried talking to support, but they can 't seem to help.

Fixes I've tried:
- Drivers: nvidia drivers/dell drivers
- updated bios, updated games, etc

- Reinstalled windows, etc

I've also put a box fan beside the laptop, run it at high speed, turned the heater off so the room temp is about 65 deg F-- this seems to give more more time between crashes.

Dell customer service tells me that this is a software problem caused because I'm trying to run games that the system wasn't designed for (never mind that they were working 2 years ago, and it also crashes while viewing photos...).

Whenever I call back, I keep getting frontline tech support that reinstalls the drivers by remote install and tells me that I shouldn't play games.  They also want me to buy the $50 dell support package to solve my "software" issues.

Any ideas?  Are there some magic words to get me in touch with someone that can REALLY help me?