Dell D430, 630, and D830
I guess it all depends on where, when, and how the laptop is to be used as it ultimately needs to do what is needed when it's needed. Running my business from home is a big difference than working on enterprise systems in mission critical data centers (if they're even still called that). That being said with the availabilty of spare parts and knowledge of the machines here's what I went with-
The Dell D430, D630, and D830 for multimedia use as well as local and remote diagnostics. All have the magnesium alloy cases and are very reasonably priced on ebay if you look for bargains. I'm planning on using the D430 as an ultra portable. Though not advertised, the D630 and D830 take 8 gig of ram, having the gm965 chipsets, and the D430 is quick enough with it's 2 gig max. Another convenient feature is they will all accept the same power adapter so I can keep an adapter plugged in at home, in the car, and keep one in my bag for onsite use. I've got xp pro 32 bit on my D430, xp vista business 64 bit to recognize the 8 gig of ram in my D630, and windows 7 64 bit ultimate for the 8 gig in my D830 which I use at home as a desktop replacement and mutlimedia machine since it has the nvidia video card in it.
There is an issue with the nvidia card and heat as many know but I use that one with a laptop cooler and as soon as ssd prices drop again I'm going to see if replacing the conventional drive with an ssd reduces the temperature inside the case. If need be I may also drill strategically placed holes in the case bottom to increase airflow.
In my opinion the ATG series D630 is over priced but I'm building a Panasonic Toughbook CF74 to use as an automotive OBD diagnostic system and heavy duty laptop as they come with dual cores, touch screens, are reasonably priced on ebay and can be configured with conveniences like a fingerprint scanner, and sd card slot.