I've just purchased an Inspiron 9100, and I'm thrilled by its power. If you're looking for a laptop to run Maya/renderman without compromising too much, then that's the right choice. For example, I'm getting 55 fps at 1650*1080 in the 3D test benchmark which is only about 20% slower that the workstations we have at work ( Dual P4 Xeon + quadro FX 1000). The Ram bandwith in Sandra is around 4500 mo/s !!!!
It seemed to me that Alienware was a bit cheaper than BOXX on a P4 laptop, but I didn't take the time to do exact point-by-point comparisons, so I could be wrong.
One question I've been meaning to ask, though, is if anyone has attempted to run Linux on any of the above. My main concern is with the Quadro FX Go 1000 chip, which does not appear to be supported by Nvidia's unified Linux driver. I understand that running Linux would void any service agreements. But what are your thoughts?