I have the Sager 5690 notebook with a 15" UXGA screen and I play HL 2 & World of Warcraft on it and it rocks!!
Also using Hammer on it to learn and create a HL2 deathmatch map.
Works great for me, with no problems at all..
Here is a review on the notebook
http://notebookforums.com/showthread.php?threadid=7008
Cronn