Well I have some time to elaborate on something DTR's and Mobile Workstations -
DTR's the hulking knee breakers that only classify as a laptop because of the form factor are in my mind useless, for the money you could get a cheep mobile laptop and a rather capable desktop for the same price, at one point they where quite a fashon item but where a nightmare battery life lasting in seconds and crappy processors and questionable integrated graphics in a "performance" machine.
However serious mobile workstations can be worth the money, for instance my Thinkpad W700ds is a true workstation, what it lacks in battery power it makes up for with power under the hood, and quality components, for instance I have a quadro graphics card two hard drives 8gb ram and a serious processor. It is not designed for mobile entertainment although it can do that very well, what I want in something massive and atleast more portable than my desktop is contained in one unit. If I had to rely on this for a primary computer I would and have while I have been deployed and i can still run 4 VM's at full pelt before I have any real issues.