My buddy had an R1. The thing was fast, powerful, and had a gorgeous 1920x1200 screen. But it had MAJOR driver problems. Known bugs in the audio firmware. Alienware replaced his laptop 5 times, but ultimately, the firmware bug was an underlying part of the R1's firmware. This guy paid 2000 for this laptop, plus extra for an extended warranty, and for some reason, others with this problem were compensated with a replacement to the much more stable R2, while he was left with a bunch of R1 refurbished parts. They finally, after screaming for weeks with their support, got them to up him to an R2. The processor was much better, but TBH, the graphics card they sent him wasn't a whole lot different in terms of practical power (going from some NVIDIA mobile SLI setup to a single mobile AMD 6870ish card). And of course, 16:10 displays had been discontinued... Ultimately, I am not sure his experience was worth it. He loves his laptop, after almost a year of technical problems that, due to the complexity of mobile setups, and a fundamental lack of support from Dell. I wouldn't recommend any alienware laptop without extensive research into compatibility with the programs you choose to run. And even then, we have found that in many cases, getting an el-cheapo Llano based system produced adequate results, with more driver support, for a quarter of the cost...
These are just too much of an unfinished headache to be able to recommend. Even with a practically unlimited budget.