This is a long and complicated question in hopes that there are some experts on computational issues on this forum. I have a $5000 (approx) budget, and somewhat specific needs for a machine. I would like to decide between a Mac Pro and a high end PC. My primary metric will be computing power per dollar, and specifically model runs per dollar over a given time. Any advice appreciated. Details are below. They are long partly because I don't have the skills to know precisely what's the most important bottleneck in my processes, so I give it all in hopes that someone can help here: I want to use the machine 1) for running Monte Carlo simulations simulations on a Windows (XP or 7) based platform, and 2) for processing large datasets in R 3) secondarily, for video editing and to have a sweet mac to use at work would be a nice bonus, but very secondary to the first. I prefer Macs to PCs, but the primary purpose of this machine will be to run Windows programs. I don't have the skills to figure out exactly what my computational bottleneck is, but I suspect the primary bottleneck is in the I/O somewhere. Processor speed helps, but isn't the critical thing. The process speeds up immensely when using a RAMDisk, and is in fact unrunnable without it. There seems to be a 100 mb/sec limit somewhere in the system on my current machines (Dell T3500 3.0 with lots of fast RAM, RAID 0, etc), but I don't know what's causing the bottleneck. My model takes about 1 hour to run a single simulation, and I'll need to do hundreds or maybe thousands on this new machine and my other cluster, so speed matters. One specific question is: in spending about this amount on a Mac Pro vs. Dell PC, which will get me better I/O, motherboard, etc? I can compare the various bits like RAM, Processor and see those numbers, but specs on the motherboard, which I presume matters for I/O, are rarely offered. Or does this even matter? Anyhow, this is a shot in the dark, as I'm not even sure I'm asking the right question, but basically where do I get more computational power per dollar, Mac Pro in Bootcamp mode, or Dell workstation? Thanks!