Dell :: M4400 As A Workstation - Quality

I've been a diehard thinkpad fan for years and I'm looking to upgrade from my T60p. I love the build quality, but I've been reading too many issues with the FireGL V5700 in the new W500 series. Moreover, I've read good things about overclocking the Quadro M770 to get closer to the M1700 speeds. So I'm now looking at the Dell M4400, normally I abhor the chassis construction of Dells, but the all magnesium casing of the 4400 series looks very good.

First, coming from a thinkpad, will I be satisfied with the build quality of the Dell?

Second, I'll be primarily using autocad, rhino and 3ds Max and have a question about the effect of screen resolution on the acceleration of the viewport displays in the various programs. Normally, I'd get the highest resolution screen possible, but will there be significant performance degradation from sxga+ (1440x900) to the wuxga (1920x1280) display when using these viewport accelerated programs due to the more demanding resolution?

Third, considering that the system uses DD2 memory, will I be able to upgrade the cpu to other Core2 ES chips that you can find on ebay? It looks like these chips use pins, I haven't been keeping up to date with the new mobile intel chips, are they all pga rather than bga format now?

And finally, when can i except some sort of deal on these systems on either the Canadian or American sites? I've been seeing a lot of 30% deals on inspirons and xps systems, but not on the precisions.