Build quality is average. Not to IBM standards, but ok enough for most people.
I tend to disagree. The build quality of the Latitude laptops is quite good, still not quite up there with some business class laptops (IE IBM, Compaq Evos, etc). Inspiron is a lower build quality decent but ok for most people.
FYI major differaces between D500/600m
D500 Intel Extreme Graphics /w shared RAM--600m Radeon 9000 32/64mb
D500 better build quality real Alunimum LCD back cover instead of plastic with metal frame
D500 1.2 inches thick -- 600m 1.3 inches thick
I think thats about it. Overall I would go for the 600m, the Intel Extrme graphics just sux. Or better yet the D600 (which is basically the 600m, but is a Latitude and better build. But costs more of course.