Damaged onboard memory, a bios mod to reduce it and possibly disable bad part?

I received Amilo Xa2528 laptop today. It does boot and function otherwise well except for the graphics. Image has artifact patterns but with Windows XP's generic driver the system works fine, artifacts are not increasing. This laptop has GeForce 8600M -based GPU which is known for its unreliability, but in this case I suspect bad ram. When I installed drivers the problems got worse and XP did hang.



Is there a way to disable the bad part of memory and make the machine to work, perhaps a bios mod?



EDIT: Here is a screenshot, artifact patterns are now different when booting into safe mode by pressing F8:



http://lolled.net/kuvaus2/out.php?i=6588_DSCN8618.JPG