Curious: Are you interested in the Blu-Ray feature, or was that just something those models had? I've noticed a lot of computers don't even have optical drives anymore. I suppose it makes sense though with the rise of high speed internet, flash drives, and portable hard drives with many times the capacity of an optical disc. It's been a long time since I've really used any optical disks. Maybe occasionally for movie watching, but even that seems to be getting rare.
As for advice on what computer to buy, I'm somewhat doubtful about any advice I can give. I've bought a total of 1 computer in my lifetime, from a second hard store. I bought it more for the price than the specs. Mind you, the specs were quite a bit better than my previous computer which was probably about a decade old. I also haven't been keeping up with much lately, other than perhaps hard drives.
I do have an Acer laptop. It's probably better than my desktop, and I've been reasonably happy with it. I don't much like using laptops though, so I hardly ever use it. I much prefer the mouse/keyboard/monitor setup of a desktop, and I worry less about leaving a desktop running all day. The laptop is the only computer I have that can handle "newer" games (like say Warcraft III, or Star Wars Battlefront). The one major downside was terrible battery life. I can maybe get about 1 hour out of it, depending on what I'm doing. I've tried switching modes between performance, balanced, and power saver, but I'm still unlikely to get 2 hours out of it. Not too big of a deal though, since I rarely ever use a laptop away from a power source.
I also have an old Dell laptop where the optical drive can be removed and a second batter pack can be plugged in. I've managed to get that thing to run for probably about 12+ hours on battery once. I was programming at the time though, so that was basically just word processing. Plus, it had a hotkey to turn the screen off if I needed to step away for a couple minutes or do some extended thinking. You'd be surprised how much such a simple feature can stretch your battery life.
In the absence of intense computational need, I would generally recommend something cheap. I find most computers out there today are pretty adequate for most uses. If you're heavy into gaming, or doing scientific computation, you may need to spend a little more though. I'm not sure how intensive those models you mentioned are. Do you know if they are multithreaded? If the models you need to run are multithreaded, having extra cores can really help. If they're not multithreaded, than all you can do is find a faster CPU. Unless the models can run the computation on a graphics card, then you're often best to get a good GPU. The parallel processing powers of a good GPU can apparently outperform some multicore CPUs, provided you believe some of the stuff I've read. I don't have any experience with GPU processing for scientific needs though, so I can't really say personally. I do often see lots of reference to this sort of thing though, so it might be worth looking into. You'd have to check with the models you want to run though to see what can be done with them.
